A study looks at how much low-level arsenic exposure impacts fetal growth. And, is there a link between intimate partner violence and adverse birth outcomes? Plus: Should all elective early-term deliveries be avoided?
Results from a new study published in Environmental Health Perspectives seem to indicate that fetal growth may be negatively impacted by maternal arsenic exposure during pregnancy.
The researchers looked at 706 mother-infant pairs with low-level arsenic exposure via drinking water and diet during pregnancy. Maternal levels of second-trimester urinary arsenic and self reports about prepregnancy weight were used to assess in utero arsenic exposure Birth records from medical records were used to assess the impact on birth outcomes.
The median range of total urinary arsenic (tAs; inorganic arsenic [iAs] plus monomethylarsonic acid [MMA] plus dimethylarsinic acid [DMA]) was 3.4 µg/L (1.7 – 6.0). Every doubling of tAs was linked to a 0.10-cm decrease in head circumference (95% CI: -0.19, -0.01). Similar results were seen with both MMA and DMA. Among only male infants, each doubling of tAs was linked to a 0.28-cm (95% CI: 0.09, 0.46) increase in birth length (Pinteraction = 0.04) and a similar result was seen for DMA.
Arsenic exposure was inversely tied to Ponderal Index and the associations differed by maternal weight. Each doubling of tAs was associated with a 0.55 kg/m3 lower Ponderal Index for infants born to overweight/obese mothers (95% CI: -0.82, -0.28, P<0.001). This was not seen in infants born to normal weight mothers. A significant interaction was seen between birth weight and the mother’s weight status, the infant’s sex, and arsenic exposure (Pinteraction = 0.03). Among girls born to overweight/obese mothers, each doubling of tAs was tied to a 62.9-g decrease in birth weight (95% CI: -111.6, -14.2). However, the link was null in the other strata.
The researchers concluded that low-level arsenic exposure may have a negative impact on fetal growth and that the mother’s weight and the infant’s sex may alter the association.
A link between intimate partner violence and adverse birth outcomes?
In addition to the myriad other negative effects of intimate partner violence, when it occurs during pregnancy, it may increase the risk of a number of adverse birth outcomes, including preterm birth. That was the conclusion of investigators who reported on the results of a new literature analysis, published in BJOG.
The investigators searched PubMed and SCOPUS through May 2015 for observational studies that compared the rate of at least one adverse birth outcome (small-for-gestational age [SGA] infant, preterm birth, and low-birthweight infants) among women who had experience with intimate partner violence with that in women who had no such history. Overall, 50 observational studies met their criteria and were evaluated.
The authors found that intimate partner violence was significantly linked to both preterm birth (odds ratio [OR] 1.91, 95% CI 1.60–2.29) and low birth weight (OR 2.11, 95% CI 1.68–2.65). The investigators did note that there was a high level of heterogeneity present for both outcomes (I2 = 84 and 91%, respectively). The link to SGA was found to be less pronounced and only marginally significant (OR 1.37, 95% CI 1.02–1.84), but only 7 studies were available for that meta-analysis.
The researchers concluded that women who experience intimate partner violence are at increased risk for several adverse birth outcomes. They urged further study on the association between intimate partner violence and SGA infants.
Should all elective early-term deliveries be avoided?
A large retrospective cohort study casts doubt on the belief that all elective early-term deliveries should be avoided. The results of the research, conducted in 125 birthing centers in Florida, were published online in Obstetrics & Gynecology.
The authors looked at whether neonatal morbidity and infant mortality differed for elective early-term deliveries or those expectantly managed and delivered at ≥39 weeks’ gestation. The data, on 675,302 singleton births from 2005 to 2009 in Florida, were from a validated, longitudinally linked maternal and infant database. The study population was categorized into exposure groups based on the timing and reasons for delivery initiation.
Four subtypes of deliveries at 37 to 38 weeks’ gestation were compared to a group of expectantly managed infants delivered at 39 to 40 weeks’ gestation. Primary outcomes included neonatal respiratory morbidity, sepsis, feeding difficulties, neonatal intensive care unit (NICU) admission, and infant mortality.
Among the infants delivered early-term compared with those delivered at 39 to 40 weeks’ gestation, the researchers found no higher risks of neonatal respiratory morbidity, sepsis, or NICU admission. However, they did have slightly higher risks of feeding difficulty (odds ratio 1.18, 99% confidence interval, 1.02 to 1.36). Risks of adverse outcomes were increased by 13% to 66% in infants delivered by cesarean section at 37 to 38 weeks’ gestation. Compared with the expectant management group, the infants who were delivered early by induction and cesarean had similar survivor experiences.
The authors concluded that “the issues surrounding the timing and reasons for delivery initiation are complicated and each pregnancy is unique.” Their study “cautions against a general avoidance of all elective early-term deliveries.”