The effect of paternal age on fetal birth outcomes.

Research investigating the role of paternal age in adverse birth outcomes is limited. This population-based retrospective cohort study used the Missouri maternally linked data set from 1989 to 2005 to assess whether paternal age affects fetal birth outcomes: low birth weight (LBW), preterm birth (PTB), stillbirth, and small size for gestational age (SGA). We examined these outcomes among infants across seven paternal age-groups (<20, 20-24, 25-29, 30-34, 35-39, 40-45, and >45 years) using the generalized estimating equation framework. Compared with infants born to younger fathers (25-29 years), infants born to fathers aged 40 to 45 years had a 24% increased risk of stillbirth but a reduced risk of SGA. A 48% increased risk of late stillbirth was observed in infants born to advanced paternal age (>45 years). Moreover, advanced paternal age (>45 years) was observed to result in a 19%, 13%, and 29% greater risk for LBW, PTB, and VPTB (very preterm birth) infants, respectively. Infants born to fathers aged 30 to 39 years had a lower risk of LBW, PTB, and SGA, whereas those born to fathers aged 24 years or younger had an elevated likelihood of experiencing these same adverse outcomes. These findings demonstrate that paternal age influences birth outcomes and warrants further investigation.

Interpregnancy body mass index changes and risk of stillbirth.

BACKGROUND/AIMS: To examine the association between interpregnancy body mass index (BMI) change and stillbirth. METHODS: Retrospective study using Missouri maternally linked cohort files (1978-2005). A total of 218,389 women were used in the analysis. BMI was classified as: underweight (<18.5), normal (18.5-24.9), overweight (25-29.9), or obese (≥30.0). Weight change was defined based on BMI category (i.e. normal-normal, normal-obese, etc.). Cox proportional hazard regression models were used to generate adjusted hazard ratios (HR) and 95% CI for the risk of stillbirth in the second pregnancy. RESULTS: Significant findings were associated with interpregnancy BMI changes involving overweight mothers becoming obese (HR = 1.4, 95% CI 1.1-1.7), normal-weight mothers becoming overweight (HR = 1.2, 95% CI 1.0-1.4) or obese (HR = 1.5, 95% CI 1.1-2.1), or obese mothers maintaining their obesity status across the two pregnancies (HR = 1.4, 95% CI 1.2-1.7). Other weight change categories did not show significant risk elevation for stillbirth. CONCLUSIONS: BMI change appears to play an important role in subsequent stillbirth risk.

Changes in prepregnancy body mass index between pregnancies and risk of gestational and type 2 diabetes.

INTRODUCTION: We investigated whether changes in interpregnancy body mass index (BMI) influence the risk of gestational and type 2 diabetes among a cohort of women with two consecutive live, singleton births of 20-44 weeks gestation (n = 232,272). METHODS: Logistic regression models were used to examine the risk for development of gestational or type 2 diabetes during the second pregnancy. Mothers with normal weight for both pregnancies (normal-normal) served as the referent group. RESULTS: Across all BMI categories, mothers with significant weight gain (i.e., moving from a lower BMI category into a higher category) had an increased risk for the development of diabetes. Mothers who moved from normal prepregnancy weight (BMI = 18.5-24.9 kg/m²) in the first pregnancy to obese prepregnancy weight (BMI ≥ 30.0 kg/m²) in the second pregnancy showed the greatest increment in risk. These mothers exhibited a threefold risk for developing diabetes (OR = 3.21, 95% CI 2.76-3.73). Mothers who maintained their interpregnancy BMI weight category or who moved to a lower BMI category had reduced risk for gestational and type 2 diabetes. The risk associated with mothers who moved to a lower BMI category was approximately half that of the normal-normal BMI category. CONCLUSION: Interpregnancy weight gain is associated with a dose-response increase in risk of diabetes. Establishing a normal interpregnancy BMI may reduce the risk of diabetes.