WHAT'S KNOWN ON THIS SUBJECT: Population-based references of birth weight for gestational age are useful indices of birth size in clinical and research settings. WHAT THIS STUDY ADDS:This article uses 2009-2010 US natality data and corrects for likely errors in gestational age dating to yield an up-to-date birth weight for gestational age reference. abstract OBJECTIVES: To provide an updated US birth weight for gestational age reference corrected for likely errors in last menstrual period (LMP)-based gestational age dating, as well as means and SDs, to enable calculation of continuous and categorical measures of birth weight for gestational age. METHODS:From the 2009-2010 US live birth files, we abstracted singleton births between 22 and 44 weeks of gestation with at least 1 nonmissing estimate of gestational age (ie, LMP or obstetric/clinical) and birth weight. Using an algorithm based on birth weight and the concordance between these gestational age estimates, implausible LMPbased gestational age estimates were either excluded or corrected by using the obstetric/clinical estimate. Gestational age-and sex-specific birth weight means, SDs, and smoothed percentiles (3rd, 5th, 10th, 90th, 95th, 97th) were calculated, and the 10th and 90th percentiles were compared with published population-based references.RESULTS: A total of 7 818 201 (99% of eligible) births were included. The LMP-based estimate of gestational age comprised 85% of the dataset, and the obstetric/clinical estimate comprised the remaining 15%. Cut points derived from the current reference identified ∼10% of births as #10th and $90th percentiles at all gestational weeks, whereas cut points derived from previous US-based references captured variable proportions of infants at these thresholds within the preterm and postterm gestational age ranges.CONCLUSIONS: This updated US-based birth weight for gestational age reference corrects for likely errors in gestational age dating and allows for the calculation of categorical and continuous measures of birth size. Pediatrics 2014;133:844-853 AUTHORS:

Preeclampsia is diagnosed in women presenting with new onset hypertension accompanied by proteinuria or other signs of severe organ dysfunction in the second half of pregnancy. Preeclampsia risk is increased two to four-fold among women with type 1 or type 2 diabetes. The limited number of pregnant women with preexisting diabetes and difficulties associated with diagnosing preeclampsia in women with proteinuria prior to pregnancy are significant barriers to research in this high-risk population. GDM also increases preeclampsia risk, although it is unclear whether these two conditions share a common pathophysiological pathway. Non-diabetic women who have had preeclampsia are more likely to develop type 2 diabetes later in life. Among women with type 1 diabetes, a history of preeclampsia is associated with an increased risk of retinopathy and nephropathy. More research examining pathophysiology, treatment and the long-term health implications of preeclampsia among women with preexisting and gestational diabetes is needed.

Objectives: To investigate the effect of prenatal exposure to polychlorinated biphenyls (PCBs) and dichlorodiphenyl-dichloroethylene (DDE) on weight, height and body mass index (BMI) in adult female offspring of the Michigan fisheater cohort examined between 1973 and 1991. Methods: 259 mothers from the Michigan fisheater cohort were studied. Prenatal exposure to PCBs and DDE was estimated by extrapolating maternal measurements to the time that the women gave birth. 213 daughters aged 20-50 years in 2000 were identified and 83% of them participated in at least one of two repeated investigations in 2001/02 (n = 151) and 2006/07 (n = 129). To assess the effect of prenatal PCB and DDE exposure on anthropometric measurements, generalised estimating equations nested for repeated measurements (2001/02 and 2006/07) and for sharing the same mother were used. We controlled for maternal height and BMI and for daughters' age, birth weight, having been breastfed and number of pregnancies. Results: Maternal height and BMI were significant predictors of the daughters' height, weight and BMI. Low birth weight (,2500 g) was significantly associated with reduced adult offspring weight and BMI. The weight and BMI of adult offspring were statistically significantly associated with the extrapolated prenatal DDE levels of their mothers. Controlling for confounders and compared to maternal DDE levels of ,1.503 mg/l, offspring BMI was increased by 1.65 when prenatal DDE levels were 1.503-2.9 mg/l and by 2.88 if levels were .2.9 mg/l. Prenatal PCB levels showed no effect. Conclusion: Prenatal exposure to the oestrogenic endocrine-disrupting chemical DDE may contribute to the obesity epidemic in women.

While early studies on the effects of leisure time physical activity (LTPA) during pregnancy were concerned about possible harm to the mother or fetus, these fears have not been substantiated. Instead, a growing body of literature has documented several health benefits related to pregnancy LTPA. The purpose of this article was to synthesize evidence from epidemiological studies conducted in the United States, Canada, and Scandinavia on the benefits of LTPA and exercise during pregnancy with regard to maternal health, pregnancy outcomes, and child health. We focused on studies evaluating relations between pregnancy LTPA and gestational diabetes, hypertensive disorders, excessive gestational weight gain, birth weight, timing of delivery, and child body composition. The bulk of evidence supports beneficial effects of pregnancy LTPA on each outcome; however, most previous studies have been observational and used self-reported LTPA at only one or two time points in pregnancy. Limitations of the current knowledge base and suggestions for future research on the health benefits of LTPA during pregnancy are provided.

Objective This study examined associations between maternal lipid levels at mid-pregnancy and preterm delivery, medically indicated or spontaneous. Design Prospective cohort study. Setting Women were recruited from 52 clinics in five Michigan, U.S.A communities (1998–2004). Population Pregnant women were enrolled at 15–27 weeks’ gestation and followed to delivery (n=3019). Methods A single blood sample was obtained at study enrollment. Blood lipids, i.e., total (TC), high-density lipoprotein (HDLc), low-density lipoprotein (LDLc) cholesterol, and triglycerides (TG), were measured on a subcohort (n=1,309). Main Outcome Measures There were 221 spontaneous, 100 medically indicated preterm deliveries and 988 term deliveries. Polytomous logistic regression models examined relations among cholesterol levels (Low: <10th %tile, Referent: 10th–<70th %tile, High: ≥70th %tile), quartiles of TG (Referent: first quartile) and delivery outcome (Referent: term). Results Odds of medically indicated preterm delivery were increased among women with low TC (adjusted odds ratio (aOR)= 2.04, 95% confidence interval (CI): 1.12,3.72), low HDLc (aOR=1.89, 95%CI: 1.04,3.42), or low LDLc (aOR=1.96, 95%CI: 1.09,3.54). Odds of spontaneous preterm delivery were increased among women with high TC (aOR=1.51, 95%CI: 1.06,2.15), high LDLc (aOR=1.42, 95%CI: 0.99,2.04) or high TG (aOR=1.90, 95%CI: 1.21,2.97 and aOR=1.72, 95%CI: 1.06,2.78 for third and fourth quartiles, respectively). Conclusions Extremely low TC, HDLc and LDLc were associated with a modest increase in risk of medically indicated preterm delivery, while high TC, LDLc and TG modestly increased risk of spontaneous preterm delivery. Further research is needed to uncover explanations for these associations and to identify optimal ranges for maternal lipids.

A single accelerometer placed on the thigh provided the highest accuracy for EE prediction, although monitors worn on the wrists or hip can also be used with high measurement accuracy.

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BackgroundRecent evidence suggests that physical activity (PA) and sedentary behavior (SB) exert independent effects on health. Therefore, measurement methods that can accurately assess both constructs are needed.ObjectiveTo compare the accuracy of accelerometers placed on the hip, thigh, and wrists, coupled with machine learning models, for measurement of PA intensity category (SB, light-intensity PA [LPA], and moderate- to vigorous-intensity PA [MVPA]) and breaks in SB.MethodsForty young adults (21 female; age 22.0 ± 4.2 years) participated in a 90-minute semi-structured protocol, performing 13 activities (three sedentary, 10 non-sedentary) for 3–10 minutes each. Participants chose activity order, duration, and intensity. Direct observation (DO) was used as a criterion measure of PA intensity category, and transitions from SB to a non-sedentary activity were breaks in SB. Participants wore four accelerometers (right hip, right thigh, and both wrists), and a machine learning model was created for each accelerometer to predict PA intensity category. Sensitivity and specificity for PA intensity category classification were calculated and compared across accelerometers using repeated measures analysis of variance, and the number of breaks in SB was compared using repeated measures analysis of variance.ResultsSensitivity and specificity values for the thigh-worn accelerometer were higher than for wrist- or hip-worn accelerometers, > 99% for all PA intensity categories. Sensitivity and specificity for the hip-worn accelerometer were 87–95% and 93–97%. The left wrist-worn accelerometer had sensitivities and specificities of > 97% for SB and LPA and 91–95% for MVPA, whereas the right wrist-worn accelerometer had sensitivities and specificities of 93–99% for SB and LPA but 67–84% for MVPA. The thigh-worn accelerometer had high accuracy for breaks in SB; all other accelerometers overestimated breaks in SB.ConclusionCoupled with machine learning modeling, the thigh-worn accelerometer should be considered when objectively assessing PA and SB.