Childbearing beyond maternal age 50 and fetal outcomes in the United States.

OBJECTIVE: To estimate whether achieving pregnancy beyond maternal age of 50 years compromises fetal well-being and survival. METHODS: This was a retrospective study on all deliveries in the United States from 1997 to 1999. Four maternal age groups of 20-29 (young), 30-39 (mature), 40-49 (very mature), and 50 or more years (older) were constructed to assess risk gradients for fetal morbidity and mortality. RESULTS: A total of 539 deliveries among older mothers (aged 50 and above) were documented (four per 100,000). Among singleton gestations, the risks for low birth weight, preterm, and very preterm were tripled among older mothers, whereas the occurrence of very low birth weight, small size for gestational age, and fetal mortality were approximately doubled compared with those for young mothers. Older mothers also had greater risks for fetal morbidity and mortality than their immediate younger counterparts (40-49 year olds) except for very low birth weight. Among multiple gestations, the differences in risk between older and young mothers were lower than those noted among singletons. Still, compared with young mothers, older mothers had significantly higher risks of low birth weight, very low birth weight, very preterm, and small size for gestational age. Older mothers also had higher risk estimates for multiples than 40-49-year-old gravidas in terms of all fetal morbidity and mortality indices. CONCLUSION: Pregnancy beyond age 50 was associated with increased risks for the fetus. Our findings suggest that this age group is a distinct obstetric high-risk entity that requires special counseling before and after conception.

Infant mortality among twins born to teenagers in the United States. Black-white disparity.

OBJECTIVE: To determine the magnitude of the disparity in infant mortality between twins born to black and white teenagers in the United States. STUDY DESIGN: Analysis was performed on twins born to adolescents in the United States within the period 1995-1997. The generalized estimating equations framework was used to generate relative risks after capturing the effects of sibling correlations within twin pairs. RESULTS: Infant mortality was 20% higher among black twins as compared to their white counterparts (adjusted OR = 1.20, 95% CI = 1.04-1.39). The black-white disparity in infant mortality occurred exclusively in the neonatal period (adjusted OR = 1.31, 95% CI = 1.11-1.54), with postneonatal estimates comparable (adjusted OR = 0.86, 95% CI = .63-1.17). The higher proportion of low-birth-weight infants--more specifically, those small for gestational age as opposed to preterm--among black twins was the most likely explanation for the lower survival probability among twins born to black teenagers. CONCLUSION: Black-white disparity in infant mortality among twins occurred exclusively during the first 28 days of life rather than throughout infancy. Efforts to bridge the gap should be focused on this critical period and should preferentially target those twins who are small for gestational age.

Smoking-associated fetal morbidity among older gravidas: a population study.

BACKGROUND: We set out to assess the influence of advanced maternal age on fetal morbidity associated with smoking during pregnancy in a population-based retrospective study of 7 792 990 singleton live births between 1995 and 1997 in the United States with documented maternal smoking habit. METHODS: The study group consisted of infants born to mothers aged>or=40 years (older mothers). Two maternal age categories (20-29, "younger mothers"; 30-39, "mature mothers") were constructed as comparison groups. Adjusted odds ratios (ORs) generated from logistic regression models were used to compare fetal morbidity indices associated with smoking across maternal age categories. Main outcome measures included preterm, very preterm, and small for gestational age (SGA). RESULTS: The prevalence of smoking was 13.1%, and decreased with increasing maternal age. Regardless of maternal age, the risk for fetal morbidity was significantly elevated if the mother smoked. The risks for preterm and SGA associated with smoking were significantly higher among older gravidas as compared to younger mothers while mature mothers had risk estimates comparable to those of older mothers. Among smoking mothers only, the risk pattern for fetal morbidity was J-shaped, with babies of older smokers having significantly higher fetal morbidity indices, while those of mature smokers showed lower levels of risk as compared to younger mothers. CONCLUSION: In an era of relatively lower prevalence of smoking during pregnancy, advanced maternal age still increases the risk of smoking-associated fetal morbidity. Our findings reveal new information of elevated risk for very preterm births among older smoking mothers.

Impact of maternal anaemia on birth outcomes of teen twin pregnancies: a comparative analysis with mature young mothers.

We investigated the impact of maternal anaemia on birth outcomes among adolescent twin pregnancies in the United States using the vital statistics records for matched multiple births covering the years 1995-1997 inclusive. The study group consisted of mothers aged 19 years or younger who had a twin pregnancy. A cohort of women aged 20-29 years with twin pregnancies served as the comparison group. The main birth outcomes of interest were: low and very low birth weight, preterm and very preterm delivery, small-for-gestational age, stillbirth, neonatal and perinatal mortality. Crude and adjusted odds ratios for the above outcomes were calculated using the generalised estimating equation framework (GEE) that captured both intra- and intercluster sources of heterogeneity. Although not statistically significant, we detected an elevated risk for stillbirth among anaemic women (20-30%) in either age cohort, a magnitude that is substantial at the population level as well as warranting further aetiological investigations.

Stillbirths and infant deaths associated with maternal smoking among mothers aged > or =40 years: a population study.

We set out to estimate the association between smoking among pregnant women aged at least 40 years and pregnancy outcome by analyzing singleton live births in the United States between 1995 and 1997. The study group consisted of deliveries to mothers aged 40 years and older with two maternal age categories (20 to 29 and 30 to 39 years) as control. Although risks varied with maternal age, smoking was associated with a higher-than-expected risk for infant mortality in all maternal age categories. The highest rate of infant mortality associated with smoking after adjusting for confounding was among mothers aged 20 to 29 (hazard ratio [HR], 1.49; 95% confidence interval [CI], 1.28 to 1.75), while the lowest was among pregnant mothers in the 40 and above age category (HR, 1.03; 95% CI, 0.87 to 1.23). In utero fetal demise was highest among older smoking mothers (>/=40 years) and declined with decreasing age (p for trend <0.0001). In conclusion, the relationship between maternal smoking and pregnancy outcomes is modified by the age of the mother.