No abstract

Reported last menstrual period (LMP) is commonly used to estimate gestational age (GA) but may be unreliable. Ultrasound in the first trimester is generally considered a highly accurate method of pregnancy dating. The authors compared first trimester report of LMP and first trimester ultrasound for estimating GA at birth and examined whether disagreement between estimates varied by maternal and infant characteristics. Analyses included 1867 singleton livebirths to women enrolled in a prospective pregnancy cohort. The authors computed the difference between LMP and ultrasound GA estimates (GA difference) and examined the proportion of births within categories of GA difference stratified by maternal and infant characteristics. The proportion of births classified as preterm, term and post-term by pregnancy dating methods was also examined. LMP-based estimates were 0.8 days (standard deviation = 8.0, median = 0) longer on average than ultrasound estimates. LMP classified more births as post-term than ultrasound (4.0% vs. 0.7%). GA difference was greater among young women, non-Hispanic Black and Hispanic women, women of non-optimal body weight and mothers of low-birthweight infants. Results indicate first trimester report of LMP reasonably approximates gestational age obtained from first trimester ultrasound, but the degree of discrepancy between estimates varies by important maternal characteristics.

Our results do not suggest an adverse effect of haloacetic acid or total organic halide exposure on fetal growth. An association of TTHM with SGA was seen only for average residential concentrations above the current regulatory standard.

The probability of preterm birth was not increased with high DBP exposure.

Purpose-We examined the association between endometriosis and exposure to polybrominated biphenyls (PBBs) and polychlorinated biphenyls (PCBs) among women inadvertently exposed to PBBs in 1973.Methods-Serum PBB and PCB were measured in the late 1970s. Women self-reported endometriosis at interview in 1997. We constructed Cox models to estimate the relative incidence of endometriosis in relation to PBB and PCB levels.Results-Seventy-nine of 943 women (9%) reported endometriosis. Compared to women with low PBB exposure (≤ 1 parts per billion [ppb]), women with moderate PBB (1-4 ppb) (hazard ratio [HR] = 0.72; 95% confidence interval [CI], 0.39-1.31) and high PBB (≥ 4 ppb) (HR = 0.90; 95% CI, 0.51-1.59) exposure did not have increased incidence of endometriosis. Increased incidence of endometriosis was suggested among women exposed to moderate PCB (5-8 ppb) (HR = 1.67; 95% CI, 0.91-3.10) and high PCB (≥ 8 ppb) (HR = 1.68; 95% CI, 0.95-2.98) levels compared to low PCB exposure (≤ 5 ppb).Conclusions-Our study does not support an association between PBB exposure and endometriosis. Findings for serum PCB level are consistent with an emerging body of literature suggesting an association between PCB exposure and endometriosis.