Faculty Bibliography

OBJECTIVE: To determine the association between moderate and vigorous physical activities (MVPA) during midpregnancy and the risk of hyperglycemia. METHODS: Data were from 1437 pregnant women. Frequency, duration, and intensity of MVPA during the previous 7 days were collected via questionnaire at 17-22 weeks' gestation. Modes of MVPA included work, recreation, transportation, caregiving, and indoor and outdoor household activities. Hyperglycemia was defined as a glucose concentration >/=130 mg/dL on a 1-hour, 50-g glucose challenge test or gestational diabetes mellitus (GDM) assessed at ~27 weeks' gestation. Multivariable Poisson regression estimated risks of hyperglycemia associated with total and mode-specific MVPA. RESULTS: There were 269 women (18.7%) with hyperglycemia. Any metabolic equivalent (MET) hours/week of recreational MVPA was associated with a 27% lower risk of hyperglycemia (adjusted relative risk, [aRR] 0.73, 95% confidence interval [95%CI] 0.54-0.99). Multiplicative interaction terms were significant for prepregnancy body mass index (BMI) and recreational MVPA (p=0.01). Among women with prepregnancy BMI <25 kg/m(2), recreational MVPA was associated with a 48% lower risk of hyperglycemia (aRR 0.52, 95%CI 0.33-0.83) compared to women who reported none. There was no association of hyperglycemia and recreational MVPA among women with prepregnancy BMI <25 kg/m(2). CONCLUSIONS: Recreational MVPA during pregnancy is associated with a lower risk of hyperglycemia, specifically among women with prepregnancy BMI <25 kg/m(2). Further research is warranted to determine recommended amounts and intensities of physical activity and to discern whether there are differences in the effects of physical activity between specific modes of physical activity or among subgroups of women in relation to hyperglycemia.

OBJECTIVE: To determine how gestational weight gain (GWG), categorized using the 2009 Institute of Medicine recommendations, relates to changes in offspring weight-for-age (WAZ), length-for-age (LAZ) and weight-for-length z-scores (WLZ) between early infancy and 3 years. METHODS: Women with singleton infants were recruited from the third cohort of the Pregnancy, Infection, and Nutrition Study (2001-2005). Term infants with at least one weight or length measurement during the study period were included (n = 476). Multivariable linear mixed effects regression models estimated longitudinal changes in WAZ, LAZ and WLZ associated with GWG. RESULTS: In early infancy, compared with infants of women with adequate weight gain, those of women with excessive weight gains had higher WAZ, LAZ and WLZ. Excessive GWG >/= 200% of the recommended amount was associated with faster rates of change in WAZ and LAZ and noticeably higher predicted mean WAZ and WLZ that persisted across the study period. CONCLUSIONS: GWG is associated with significant differences in offspring anthropometrics in early infancy that persisted to 3 years of age. More longitudinal studies that utilize maternal and paediatric body composition measures are necessary to understand the nature of this association.

BACKGROUND: Current validated neonatal body composition methods are limited/impractical for use outside of a clinical setting because they are labor intensive, time consuming, and require expensive equipment. The purpose of this study was to develop an anthropometric model to estimate neonatal fat mass (kg) using an air displacement plethysmography (PEA POD(R) Infant Body Composition System) as the criterion. METHODS: A total of 128 healthy term infants, 60 females and 68 males, from a multiethnic cohort were included in the analyses. Gender, race/ethnicity, gestational age, age (in days), anthropometric measurements of weight, length, abdominal circumference, skin-fold thicknesses (triceps, biceps, sub scapular, and thigh), and body composition by PEA POD(R) were collected within 1-3 days of birth. Backward stepwise linear regression was used to determine the model that best predicted neonatal fat mass. RESULTS: The statistical model that best predicted neonatal fat mass (kg) was: -0.012 -0.064*gender + 0.024*day of measurement post-delivery -0.150*weight (kg) + 0.055*weight (kg)2 + 0.046*ethnicity + 0.020*sum of three skin-fold thicknesses (triceps, sub scapular, and thigh); R2 = 0.81, MSE = 0.08 kg. CONCLUSIONS: Our anthropometric model explained 81% of the variance in neonatal fat mass. Future studies with a greater variety of neonatal anthropometric measurements may provide equations that explain more of the variance.

PURPOSE: Previous studies suggest that hair products containing endocrine disrupting chemicals could alter puberty. We evaluated the association between childhood hair product use and age at menarche in a racially diverse study population. METHODS: We recruited 300 African-American, African-Caribbean, Hispanic, and white women from the New York City metropolitan area who were between 18-77 years of age. Data were collected retrospectively on hair oil, lotion, leave-in conditioner, perm, and other types of hair products used before age 13. Recalled age at menarche ranged from 8 to 19 years. We used multivariable binomial regression to evaluate the association between hair product use and age at menarche (<12 vs. >/=12), adjusting for potential confounders. RESULTS: African-Americans were more likely to use hair products and reached menarche earlier than other racial/ethnic groups. Women reporting childhood hair oil use had a risk ratio of 1.4 (95% confidence interval [CI]: 1.1-1.9) for earlier menarche, adjusting for race/ethnicity and year of birth. Hair perm users had an increased risk for earlier menarche (adjusted risk ratio = 1.4, 95% CI: 1.1-1.8). Other types of hair products assessed in this study were not associated with earlier menarche. CONCLUSIONS: Childhood hair oil and perm use were associated with earlier menarche. If replicated, these results suggest that hair product use may be important to measure in evaluating earlier age at menarche.

OBJECTIVE: To determine whether pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) influence infant postnatal growth. STUDY DESIGN: Participants were from the Pregnancy, Infection, and Nutrition study, a prospective pregnancy cohort. Term infants with weight or length measurements at approximately 6 months were included (n = 363). Multivariable regression estimated associations for weight-for-age (WAZ), length-for-age (LAZ), and weight-for-length z-scores (WLZ) and rapid infant weight gain with categorical maternal exposures defined with the 2009 Institute of Medicine recommendations. RESULTS: Pre-pregnancy overweight and obesity were associated with higher WAZ (linear regression coefficient [beta], 0.32; 95% CI, 0.04-0.61) and WLZ (beta, 0.39; 95% CI, 0.02-0.76), respectively. Pre-pregnancy BMI was not associated with LAZ. Excessive GWG was associated with higher WAZ (beta, 0.39; 95% CI, 0.15-0.62) and LAZ (beta, 0.34; 95% CI, 0.12-0.56). Excessive GWG >/= 200% of recommended amount was associated with higher WAZ (beta, 0.68; 95% CI, 0.28-1.07), LAZ (beta, 0.45; 95% CI, 0.06-0.83), and WLZ (beta, 0.43; 95% CI, 0.04-0.82). Risk of rapid weight gain increased across maternal exposure categories; however, none of the estimates were significant. CONCLUSIONS: Pre-pregnancy BMI and GWG are modifiable intrauterine exposures that influence infant postnatal anthropometric outcomes. Further investigation with infant body composition measurements is warranted.

OBJECTIVE: The objective of the study was to determine the association between child BMI at age 3 years and maternal glucose concentration among women without pre-existing diabetes or a gestational diabetes mellitus (GDM) diagnosis. RESEARCH DESIGN AND METHODS: Data are from the Pregnancy Infection and Nutrition and Postpartum studies and include 263 mother-child pairs. Measured weights and heights at 3 years were used to calculate age- and sex-specific BMI z scores and percentiles. Multivariable linear regression models were used to examine associations of continuous BMI z scores with maternal glucose concentration. Modified Poisson regression estimated risk ratios of child overweight/obesity (BMI >/= 85th percentile). RESULTS: The mean (SD) maternal glucose concentration and prepregnancy BMI were 103.8 (23.7) mg/dL and 24.3 (5.9) kg/m(2), respectively. At 3 years, the mean (SD) child BMI z score was 0.29 (0.99), 20.9% were overweight/obese and 5.3% were obese. In the adjusted model, when compared with glucose concentration <100 mg/dL, a concentration >/= 130 mg/dL was associated with significantly higher child BMI z score at 3 years (estimated z score difference of 0.39 [95% CI: 0.03-0.75]). With the use of the same reference category, a concentration >/= 130 mg/dL was associated with an approximate twofold greater risk of child overweight/obesity (adjusted risk ratio 2.34 [95% CI: 1.25-4.38]). CONCLUSIONS: Fetal exposure to high maternal glucose concentration in the absence of pre-existing diabetes or GDM may contribute to the development of overweight/obesity in the offspring, independent of maternal prepregnancy BMI.