Sudden infant death syndrome: risk factor profiles for distinct subgroups

The authors investigated risk profiles of sudden infant death syndrome (SIDS) as a function of age at death. A case-control study carried out in the Tyrol region of Austria enrolled 99 infants who died of SIDS between 1984 and 1994 and 136 randomly selected controls. Early and late SIDS (< 120 days of age vs. > or = 120 days) were defined according to the clear-cut bimodal age-at-death distribution. Inadequate antenatal care, low parental social and educational level, and the prone sleeping position were risk conditions that applied to both early and late SIDS. A marked seasonal variation (winter preponderance) was the most outstanding feature of late SIDS. A gestational age of < 37 weeks (odds ratio (OR) = 8.4, 95% confidence interval (CI) 2.6-26.0), repeated episodes of apnea (OR = 5.7, 95% CI 1.2-27.0), low birth weight (< 2,500 g) (OR = 3.4, 95% CI 1.1-11.0), a family history of sudden infant death (OR = 2.9, 95% CI 1.1-7.5), and maternal smoking during pregnancy (OR = 2.2, 95% CI 1.0-4.5) were associated with early SIDS. This study identified two distinct subgroups of SIDS infants characterized by different risk conditions and ages at death. These results underline a multiple-cause hypothesis for SIDS etiology which involves a genetic predisposition, immaturity in the first months of life, and environmental factors acting at various ages.     

Ethnic differences in the sudden infant death syndrome: what we can learn from immigrants to the UK

AIMS: To compare the effect of potential maternal and birth factors on rates of sudden infant death syndrome (SIDS) within and between infants born to mothers of different ethnic groups. METHODS: Routinely collected obstetric, child health data relating to 39,101 residents of three East London Districts born in 1989-1990 were obtained. These were matched with 312 death registration records to validate death and add registered cause of death. Mortality rates were calculated in the usual way, and using life-table methods. RESULTS: These related to six ethnic groups, the largest of which were Anglo-European and Bangladeshi. Low birth-weight was the only factor associated with a greater risk of SIDS in all ethnic groups. Maternal smoking was uncommon amongst all Asian groups and African mothers, and rates of SIDS were uniformly low amongst non-smokers in all ethnic groups except Pakistanis. Adjustment for maternal age, parity, gestational age and birthweight would widen the differences between risk of SIDS observed between Anglo-Europeans and Bangladeshi infants. CONCLUSIONS: The study has demonstrated that local data is more timely and of greater detail than that available nationally. Of the risk factors considered, smoking reported during pregnancy is the most commonly encountered and is particularly associated with deaths attributed to SIDS.     

A record-linkage study on risk factors for cause-specific infant mortality

Infant death certificates were linked with birth certificates for infants born to residents of Tohoku, Tokai and Kyushu regions in 1989 (n = 409, 679, or about one-third of all births in Japan), to examine the effects of variables, as reported on birth certificates, on cause-specific infant mortality. "Certain conditions originating in the perinatal period" and "congenital anomalies" accounted for nearly 90 percent of neonatal deaths, while "congenital anomalies", "injuries and poisoning" and "sudden infant death" were responsible for about 65 percent of postneonatal deaths. Mortality rates for almost all causes of infant deaths, except injuries and poisonings, increased as birth weight decreased not only in the neonatal period but also in the postneonatal period. This suggests that low birth weight places some infants at higher risk of death, and conditions that lead to low birth weight independently contribute to the risk of infant death. Cox's proportional hazards linear model was used to assess the effects of variables on infant mortalities by causes of death. An extremely strong birth weight effect was noted for "certain conditions originating in the perinatal period" and "congenital anomalies". Being a male infant and late order of birth in multiparity were other risk factors for deaths from "congenital anomalies", while being a male infant, resident of Tohoku region and maternal stillbirth experience related to deaths from "certain conditions originating in the perinatal period". Elevated risks of sudden infant death syndrome (SIDS), of which mortality rate in Japan was considerably lower than those in most developed Western countries, i.e. 0.23 per 1,000 live births in 1989, were associated with low birth weight, being a male infant, low maternal age, late order of birth in multiparity and illegitimacy. Low maternal age, late order of birth in multiparity and illegitimacy, also, related significantly to increased risk of infant deaths for "injuries and poisoning". These results suggest the independent contributions of socioeconomic factors to infant mortality, especially postneonatal mortality, from SIDS, "injuries and poisonings".     

Primary intrasellar mixed germ-cell tumor with precocious puberty and diabetes insipidus

A case-control study using data from the Baltimore-Washington Infant Study (BWIS) examined possible paternal risk factors in the etiology of isolated membranous ventricular septal defects (VSD). There were 641 total VSD case infants and 3,549 randomly selected control infants ascertained between 1981 and 1989. Isolated membranous VSDs were identified in 499 cases. Socio-demographic factors (such as parental age and race), social habits, and medical conditions were analyzed by multiple logistic regression in order to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI). Paternal age was not found to be a risk factor per se, but small positive associations were found for some social habits and maternal factors. Significant associations were found for paternal marijuana use (OR 1.36, 95% CI 1.05-1.76), African-American race of the infant (OR 1.34, 95% CI 1.09-1.65), and for cocaine use among older fathers (OR 3.92, 95% CI 1.30-11.86). These associations support a multifactorial etiologic hypothesis for isolated membranous VSDs and point to some interesting parental behavioral and medical considerations which may contribute to risk for this common birth defect.     

SIDS--a retrospective study in Slovakia

This is an analysis of 102 cases of SIDS from retrospective studies in the Zilina and Senica districts. The incidence of SIDS in the Zilina district was 2.04/1000 (period 1969-1978) and 1.04/1000 (period 1980-1984). The incidence of SIDS in the Senica district was 0.82/1000 (period 1979-1990). According to preliminary results of the epidemiological study of SIDS in Slovakia (1991) the incidence is only 0.89/1000 which amounts, however, to 23.1% of the post-neonatal mortality. In the investigation nine indicators were evaluated: age at the time of death, morbidity before death, place of death, education of mother, position of infant at time of death, birth weight succession of child in family. The assembled results were compared with data in the literature. Because of similar results it is assumed that the following risk factors participate in the incidence of SIDS: age (2-4 months), time between midnight and 6 a.m., low socio-economic status of family, lower education of mother, incidence of SIDS in the family, short interval between childbirths, prone position during sleep, succession of child in family (third or subsequent), effect of smoking. The investigation did not confirm as risk factors a lower birth weight and inadequate postnatal adaptation. In the conclusions some possible ways of prevention are outlined.     

Determinants of poor pregnancy outcomes among teenagers in Sweden

OBJECTIVE: To study pregnancy outcomes among teenagers and to determine whether age-related increases in risk are due to differences in socioeconomic conditions, maternal smoking, or anthropometric status. METHODS: All single births during 1990-1991 to mothers aged less than 25 years recorded in the Swedish Medical Birth Registry were studied (n = 62,433). The pregnancy outcomes analyzed were late fetal death, infant mortality, preterm birth, low birth weight, small for gestational age, and low Apgar scores. Information on maternal age, parity, family situation, maternal smoking, maternal height, and weight gain during pregnancy was recorded in the Medical Birth Registry. Information on socioeconomic characteristics was obtained from the Population Census. Logistic regression analysis was used to define the determinants of the adverse outcomes among teenagers. RESULTS: Compared with women aged 20-24 years, girls of 17 years or less were at higher risk for preterm birth (odds ratio [OR] 1.6), and this increased risk remained essentially unchanged after controlling for major confounding factors (OR 1.5). Teenagers also had a crude 50% higher risk of late fetal death and infant mortality, but this risk was reduced after controlling for the effect of socioeconomic characteristics (adjusted OR 1.2). CONCLUSIONS: The increase in risk of late fetal death and infant mortality associated with low maternal age is substantially an effect of teenagers' poorer socioeconomic situation. However, the increase in preterm birth among younger teenagers suggests that young maternal age may be a biologic risk factor for preterm birth.     

Evidence for retarded kidney growth in sudden infant death syndrome

The aim of the study was to compare the growth rate of the kidneys of infants who died of sudden infant death syndrome (SIDS) and control babies under 1 year; 227 infants who died in St. Petersburg from 1983 to 1990 and who met the criteria for SIDS were included in the study; 138 infants who died suddenly of respiratory infections within the same period constituted a control group. The infants did not have signs of dehydration, malformations, tumours or intrauterine infections. Morphologically the kidneys were intact. Factors which might influence the weight of the kidneys at the time of death were: the cause of death (whether SIDS or not), gender, gestational age, weight, length and ponderal index at birth, age, weight and length at death. Stepwise (forward) linear regression analysis identified three variables which in combination most accurately and independently influenced the predicted weight of the kidneys. These were the cause of death, gender and weight at the time of death. The weight of the kidneys increased by 6.0 g for each increase in total body weight of 1,000 g [95% confidence interval (CI) 5.0-7.0 g], in boys the kidney weight was 3.3 g (95% CI 1.6-5.0 g) higher than in girls and in the SIDS babies kidney weight was 2.5 g (95% CI 0.8-4.2 g) less than controls. Delayed kidney growth may be an indicator of increased risk of SIDS in infants under 1 year and may contribute in some cases.     

Delayed childbearing--are there any risks?

OBJECTIVE: To determine whether women delivering their first child at age 35 years or older are at increased risk of adverse (non-genetic) pregnancy outcomes. DESIGN AND SETTING: A cross-sectional analytic study of singleton deliveries in Northern Sydney Area Health Service (NSAHS) hospitals. PARTICIPANTS: All women aged > or = 20 years delivering their first child between 1 January 1990 and 31 December 1991. MAIN OUTCOME MEASURES: Obstetric complications and procedures, type of delivery and neonatal outcomes. RESULTS: Compared with women aged 20-29 years, women delivering their first child at > or = 35 years were at increased risk of pre-existing maternal hypertension (adjusted odds ratio [OR], 3.5; 95% confidence interval [CI], 1.7-7.0), antepartum haemorrhage (adjusted OR, 2.4; 95% CI, 1.6-3.7), preterm delivery (33-36 weeks) (adjusted OR, 2.0; 95% CI, 1.5-2.8) and breech presentation (adjusted OR, 1.8; 95% CI, 1.3-2.4). Women aged > or = 35 years were also substantially more likely to have an operative delivery, induced labour and/or epidural anaesthesia. Neither these women nor their infants were at increased risk of pregnancy-induced hypertension, gestational diabetes, threatened premature labour, postpartum haemorrhage, very preterm delivery (< or = 32 weeks), perinatal death, low Apgar scores or the need for neonatal resuscitation. CONCLUSIONS: Women who delay the birth of their first child face some increased risks, but these risks, for the most part, are manageable in the context of modern obstetric care.     

Maternal smoking, body mass index, and neural tube defects

The Swedish health registries were used to investigate a possible effect on the incidence of neural tube defects (NTDs) of maternal smoking and maternal body mass index (BMI) (kg/m2). Among 1,199,701 infants born in 1983-1993 with known smoking exposure in early pregnancy, 621 infants with NTDs were selected. After controlling for year of birth, maternal age, parity, education level, BMI, and immigrant status (yes/no), a highly significant, protective effect of maternal smoking on the incidence of NTDs was found. The adjusted odds ratios (OR) and (95% confidence intervals (CI)) for maternal smoking among infants with NTDs (total), anencephaly, and spina bifida were 0.75 (0.61-0.91), 0.49 (0.28-0.85), and 0.76 (0.61-0.95), respectively. A protective dose-response effect of smoking was indicated but was not statistically significant. The association between NTDs and maternal BMI found in earlier studies was supported. Women with BMI >26.0 were found to be at higher risk of having an infant with NTD compared with women in other BMI classes (adjusted OR=1.35, 95% CI 1.00-1.83). For women with BMI > or =29, the corresponding odds ratio was 1.29 (0.81-2.05). No obvious explanation was found, either for the detected association between NTDs and BMI, or for the protective effect of maternal smoking.     

Preterm and term births of small for gestational age infants: a population-based study of risk factors among nulliparous women

OBJECTIVE: To study risk factors for small for gestational age (SGA) infants by gestational age among nulliparous women and to estimate mortality rates among SGA and appropriate-for-gestational-age (AGA) infants by gestational age. DESIGN: A population-based study from the Swedish Medical Birth Register. Setting Sweden 1992 1993. POPULATION: Liveborn singleton infants to nulliparous women (n = 96,662). MAIN OUTCOME MEASURES: Crude and adjusted odds ratios of risk factors for SGA by gestational age. Rates of neonatal and postneonatal mortality. RESULTS: Older maternal age (> or = 30 years) was foremost associated with increased risks of very and moderately preterm SGA (> or = 32 weeks and 33-36 weeks, respectively), but also with term SGA (> or = 37 weeks). Risks of SGA increased with decreasing maternal height at all gestational ages. Smoking increased the risks of moderately preterm and term SGA. Short maternal education increased the risk of preterm SGA and low pre-pregnancy body mass index slightly increased the risk of term SGA. Pre-eclampsia and essential hypertension foremost increased the risk of very preterm SGA (OR = 40.5 and 32.4, respectively) and moderately preterm SGA (OR = 17.4 and 10.6, respectively), but also increased the risk of term SGA. Neonatal and postneonatal mortality rates of SGA infants were substantially influenced by gestational age, and mortality rates were consistently higher among preterm SGA infants compared with AGA infants. Conclusions: Risk factors for SGA and mortality rates among SGA infants vary by gestational age. A subdivision of risk factors by gestational age adds knowledge, particularly about risks of preterm SGA, where the highest rates of mortality were observed.     

Helicobacter pylori infection in children

BACKGROUND: Although immigrants to the United States are usually ethnic minorities and socioeconomically disadvantaged, foreign-born women generally have lower rates of low birth weight infants than do US-born women. OBJECTIVE: To measure the relationship between maternal birthplace, ethnicity, and low birth weight infants. DESIGN: Retrospective cohort study of birth certificate data. SETTING: California, 1992. SUBJECTS: Singleton infants (n = 497 868) born to Asian, black, Latina, and white women. MAIN OUTCOME MEASURES: Very low birth weight (500-1499 g), moderately low birth weight (1500-2499 g), and normal birth weight (2500-4000 g, reference category). RESULTS: Foreign-born Latina women generally had less favorable maternal characteristics than US-born Latinas, yet foreign-born Latina women were less likely to have moderately low birth weight infants (odds ratio, 0.91; 95% confidence interval, 0.86-0.96) than US-born Latinas after adjusting for maternal age, education, marital status, parity, tobacco use, use of prenatal care, and gestational age. While foreign-born Asian women generally had a less favorable profile of maternal characteristics than US-born Asians, there was no statistically significant difference in the odds of very low birth weight or moderately low birth weight infants between foreign- and US-born Asian women. Foreign-born black women had more favorable maternal characteristics than US-born women, but there was no significant nativity difference in very low birth weight or moderately low birth weight between foreign- and US-born black women after adjusting for maternal and infant factors. CONCLUSIONS: The relationship between maternal birthplace and low birth weight varies by ethnicity. Further study is needed to understand the favorable pregnancy outcomes of foreign-born Latina women.     

Fetal hemoglobin levels in sudden infant death syndrome

OBJECTIVE: The aim of this study was to determine and compare fetal hemoglobin levels from infants dying of the sudden infant death syndrome (SIDS) with aged-matched control infants dying of other causes. Similar previous studies have reported both elevated and normal levels of fetal hemoglobin in whole blood samples from infants dying of SIDS. DESIGN: Triton-acid-urea gel electrophoresis and densitometry were used to determine fetal hemoglobin levels in postmortem whole blood samples from infants dying of SIDS and from appropriately age-matched control infants. Whole blood samples were analyzed blindly and matched for postgestational age. Infant ages at death ranged from birth to less than 1 year. MAIN OUTCOME MEASURES: Fetal hemoglobin in whole blood from infants dying of SIDS and control infants. RESULTS: During the period of postnatal development most associated with SIDS cases (2 to 6 months after birth), fetal hemoglobin levels were found to be significantly elevated in postmortem whole blood samples from SIDS infants compared with gestational age-matched control infants dying of causes other than SIDS. CONCLUSION: We conclude that levels of fetal hemoglobin are elevated in postmortem whole blood of SIDS infants compared with controls. Furthermore, the apparent conflict in the literature regarding fetal hemoglobin levels in SIDS infants and controls is most likely due to variability in the control data of some studies.     

Familial and perinatal risk factors for micro- and macroalbuminuria in young IDDM patients

It has been suggested that hereditary risk for hypertension and cardiovascular disease (CVD) as well as intrauterine growth may be involved in the pathogenesis of diabetic nephropathy. In the present study, we investigated the influence of familial and perinatal risk factors on the occurrence of micro- and macroalbuminuria in young IDDM patients. A cohort of 1,150 young patients with > or =5 years' duration of IDDM was screened for microalbuminuria. Data on family history of hypertension, CVD, IDDM, and NIDDM; perinatal factors such as birth weight, gestational age, and duration of breastfeeding; and maternal education, smoking, hypertension, and proteinuria during pregnancy were collected. We identified 75 patients with an albumin excretion rate > or =15 microg/min in more than two overnight urinary samples and compared them in a nested case-control study with three normoalbuminuric control subjects per patient from the same cohort, matched for diabetes duration. Perinatal factors were analyzed in all patients born at term (+/- 2 weeks), 59 of the 75 patients and 155 of the 225 control subjects. In univariate analysis, hypertension in parents (odds ratio [OR] 4.21), CVD in parents and grandparents (OR 1.26), maternal smoking during pregnancy (OR 3.21), and a low level of maternal education (OR 2.33) were significantly associated with the development of micro- and macroalbuminuria. When adjusted for other familial and perinatal factors, current mean blood pressure, HbA1c, smoking, BMI, sex, age, and postpubertal diabetes duration, using logistic regression analyses, only parental hypertension in all patients and maternal smoking during pregnancy and low level of maternal education in full-term patients were independent risk factors. When patients with poor glycemic control were analyzed separately, familial CVD, poor metabolic control, parental hypertension, maternal smoking during pregnancy, and level of maternal education were independent risk factors, with the adjusted OR markedly increased, compared with the matched subgroup with better HbA1c. In conclusion, familial hypertension and CVD, maternal smoking during pregnancy, and low level of maternal education may independently increase the risk for incipient nephropathy in full-term offspring who later develop IDDM. Current poor glycemic control seemed to increase the effect of these risk factors.     

Proinflammatory cytokines regulate antigen-independent T-cell activation by two separate calcium-signaling pathways in multiple sclerosis patients

OBJECTIVE: The study examined the prevalence of low birth weight among biracial infants of black and white parents, by region of the United States. METHODS: Using the national linked live birth-death infant file for 1991, low birth weight (<2,500 g) was examined among 50,980 biracial singleton infants according to parental race (black mother-white father vs. white mother-black father). RESULTS: Nationally, the rate of low birth weight was 31% higher in the black mother-white father group (8.4%) than in the white mother-black father group (6.4%). The difference was smaller in the Northeast, reflecting a high rate (9.8%) for biracial infants of Puerto-Rican white mothers. The difference in the West was larger (75%), due to both a high rate in the black mother-white father group (9.1%) and a low rate for the white mother-black father group (5.2%), and persisted after controlling for parental education and a variety of maternal risk factors. CONCLUSIONS: Further studies are needed to identify the maternal factors involved in the regional differences in the prevalence of low birth weight among biracial infants.     

Potential risk factors for vertical HIV-1 transmission in Catalonia, Spain: the protective role of cesarean section. The Working Group on HIV-1 Vertical Transmission in Catalonia

OBJECTIVE: To evaluate the roles of certain potential risk factors on the vertical transmission of HIV-1. DESIGN: Prospective registry of infants born to HIV-1-infected women in Catalonia (north-east Spain) from 1987 to 1992. METHODS: A total of 599 infants, born in Catalan hospitals to 520 women who were identified as being HIV-1-infected during gestation or at delivery, were included. Data on mode of delivery, birth weight, gestational age and breast-feeding as well as the mother's age, her route of HIV-1 infection, clinical stage and p24 antigenaemia, were recorded. HIV-1 infection status of 489 (82%) of the infants was determined according to the criteria of the US Centers for Disease Control and Prevention. Risk estimates and odds ratio (OR) were calculated and logistic regression was performed. RESULTS: The overall rate of vertical transmission was 18.6% (95% confidence interval, 15.2-22.0%). Multivariate analyses revealed that Cesarean section was associated with a lower rate of vertical transmission (OR = 0.3; P = 0.001), as was maternal HIV-1 infection via injecting drug use (OR = 0.44; P = 0.02). Breast-feeding (OR = 6.9; P = 0.001), very low birth weight (< 1500 g; OR = 6.3; P = 0.001) and p24 antigenaemia (OR = 4.6; P = 0.04) were all related to increased risk. The crude rate of HIV-1 transmission was 6% among Cesarean births compared with 21% for infants born via vaginal deliveries. The population-attributable risk for vaginal deliveries was 61.7%. CONCLUSIONS: The results show a protective effect of Cesarean section in the absence of zidovudine prophylaxis. However, current research should be directed towards the individual and combined effects that antiretroviral agents and Cesarean section may have on mother-to-child HIV-1 infection.     

Preterm birth and cerebral palsy. Predictive value of pregnancy complications, mode of delivery, and Apgar scores

BACKGROUND: Preterm infants are at 8 times higher risk than term infants for pre- and perinatal brain damage, resulting in cerebral palsy. In this paper we have analysed the influence of prenatal and birth-related risk factors on cerebral palsy in preterm infants. METHODS: In a register-based study, 175 preterm singleton infants with cerebral palsy, born in 1982-86, were compared with 687 controls matched by gestational age and year of birth. RESULTS: Statistically significant higher rates in cases were found in parity > or = 3 (22% vs. 16%, p < 0.05), Cesarean section (67% vs. 56%, p < 0.01), and low Apgar scores at 1 minute (45% vs. 36%, p < 0.05). By multivariate analyses, two variables remained statistically significant: parity > or = 3 (adjusted OR = 1.53 (95% CI 1.00-2.34), p < 0.05) and Cesarean section (adjusted OR = 1.57 (95% CI 1.07-2.32), p < 0.05). CONCLUSIONS: Pregnancy complications preceding preterm birth did not imply a higher risk of cerebral palsy. Delivery by Cesarean section was a prognostic factor for developing cerebral palsy, and the predictive value of Apgar scores was highly limited.     

Maternal risk factors in infants with very low birth weight

To determine whether maternal risk factors associated with the delivery of very low birth weight infants under 1501 g are different from those associated with low birth weight infants of 1501 to 2500 g, prenatal data on 12,247 deliveries were evaluated. The sample contained 302 very low birth weight infants. Maternal race, age, height, weight, gravidity, parity, past pregnancy performance, and pregnancy complications were analyzed. Factors related to very low birth weight but not to low birth weight infants were previous abortions, previous fetal deaths, and hypertensive vascular disease. Race, maternal height, and prepregnancy weight were not related to very low birth weight but were associated with an increase in low birth weight. There was no significant difference in the rate of very low birth weight or low birth weight by maternal age from 14 to 40 years. These results contradict the concept of a uniform set of predisposing factors for birth of all infants weighing 2500 g or less.     

Maternal flu, fever, and the risk of neural tube defects: a population-based case-control study

Results of clinical and epidemiologic studies have shown an increased risk for neural tube defects (NTD) in infants whose mothers were exposed to heat during pregnancy. However, the risk for NTD in infants whose mothers had influenza during pregnancy has not been well studied. This population-based case-control study of infants born in metropolitan Atlanta, Georgia, from 1968 through 1980 included 385 infants with NTD, 3,647 infants with other birth defects, and 2,676 infants without birth defects. Of the 385 mothers of case infants, 31 reported having a 2-day or longer episode of flu with fever from 1 month before through 3 months after conception (odds ratio (OR) = 3.0; 95% confidence interval (CI) 1.9-4.7). Infants of mothers who took medications for their episodes of flu with fever had an even higher risk for NTD (OR = 4.3, 95% CI 2.6-7.1). When mothers of infants with birth defects other than NTD were used as controls, an increased risk of NTD remained for flu with fever (OR = 1.7, 95% CI 1.1-2.5). There was no increased risk for NTD among the infants of mothers who reported fever from causes other than flu. Because of the heterogeneity of maternal flu, the individual contributions of infection, fever, and medications remain difficult to disentangle.     

Bronchiolitis obliterans and no radiographic abnormalities in a patient with rheumatoid arthritis

In a case-control study, we evaluated the association of the risk of menstrual disorders with four periconceptional factors: short preceding interpregnancy interval (< 6 months), low (< or = 19 years) or high (> or = 40 years) maternal age at conception, and month of conception. We divided 919 women who had visited a fertility clinic between 1991 and 1995 into three categories: cases (with mean menstrual cycle length > or = 42 or < or = 21 days, or a variation of > or = 14 days between cycles, or amenorrhea, N = 294), controls (with cycles within a range of 25-35 days and variation < or = 7 days, N = 520), and intermediates (N = 105). A self-administrable questionnaire was mailed, asking for information about maternal reproductive history and age, and potential confounders such as smoking, exercise, and level of education. Response (77%) differed little among cases, intermediates, and controls. We found elevated risks for short pregnancy intervals [adjusted odds ratio (OR) = 2.04; 95% confidence interval (CI) = 1.04-4.02] and advanced maternal age (OR = 3.24; 95% CI = 1.27-8.30) but not for low maternal age (OR = 0.58; 95% CI = 0.11-3.14) (cases vs controls). We found similar effects for intermediates vs controls. The distribution of month of conception did not differ much from controls for both cases and intermediates. The results indicate that conception after short pregnancy intervals or at advanced maternal age increases the risk of menstrual disorders in daughters. The precise etiology is unclear, but it may lie in the quality of the oocyte at conception.     

Cell and organ culture techniques applied to the study of carcinoma of colon and rectum

The hospital records of 197 infants with the respiratory distress syndrome (RDS) were reviewed and the families of 111 of them subsequently contacted to obtain a family history. After correcting for biasis of ascertainment, the incidence of RDS among the full sibs was found to be between 12 and 19% depending on whether the individuals diagnosed as "possible RDS" were counted as affected. Among the low birth weight (LBW, less than or equal to 2.5 kg) and/or preterm (less than or equal to 37 weeks gestation) infants in the sibships, the incidence of RDS was 32-50%. Considering only sibs born after the probands yielded the empiric recurrence risk of 17--27% for all younger sibs and 39--67% for LBW/preterm younger sibs. The risk for maternal half-sibs was of about the same magnitude as that for full sibs, while the risk for paternal half-sibs was minimal. Among the LBW/preterm first cousins of probands, only the infants of maternal aunts showed an RDS incidence clearly higher than that in the general population. We think these data suggest a genetically determined maternal factor predisposing the infants of certain mothers to RDS. Other significant findings include: 1) an excess of males among the probands but a normal sex ratio among the sibs of the probands; 2) a decrease in mean birth weight and mean length of gestation for not only the probands but also their sibs; 3) a decrease in the mean parental ages at the birth of the probands; 4) a relative dearth of first-born and an excess of second-born infants among the probands; 5) an increased incidence of stillbirths in the sibships; 6) an increased number of probands born by cesarean section; and 7) a twin concordance of 75%.