Effect of obesity on neonatal outcomes in pregnancies with preterm premature rupture of membranes.

BACKGROUND: Maternal obesity is associated with increased systemic inflammation and an increased risk of preterm premature rupture of membranes. There is an established association between an inflammatory intrauterine environment and adverse neonatal outcomes that is independent of gestational age and mediated by the fetal inflammatory response. It is unknown whether the maternal systemic inflammation that is present in obese women influences the intrauterine environment and predisposes the fetus to adverse neonatal outcomes after preterm premature rupture of membranes. OBJECTIVE: The purpose of this study was to determine whether maternal obesity is associated with adverse neonatal outcomes in pregnancies that are complicated by preterm premature rupture of membranes. STUDY DESIGN: This was a secondary analysis of the Maternal-Fetal Medicine Units Network Randomized Clinical Trial on the Beneficial Effects of Antenatal Magnesium Sulfate. Women with singleton pregnancies that were affected by preterm premature rupture of membranes who delivered live-born infants between 24 + 0 and 33 + 6 weeks of gestation were included. An adverse neonatal outcome was defined as a composite outcome of neonatal death, severe necrotizing enterocolitis, respiratory distress syndrome, sepsis, or severe intraventricular hemorrhage. The rates of the composite outcome were compared between obese (body mass index, ≥30 kg/m(2)) and nonobese women. Multivariable logistic regression was used to evaluate the independent effect of obesity on neonatal outcomes. Magnesium sulfate administration, steroid administration, maternal diabetes mellitus, gestational age at delivery, indomethacin exposure, birthweight, and chorioamnionitis were all considered as possible covariates in the multivariable regression models. RESULTS: Three hundred twenty-five of the 1288 women (25.2%) who were included were obese, and 202 of these women (62.2%) had neonates with adverse outcomes. In univariable analysis, maternal prepregnancy obesity was associated with increased odds of an adverse neonatal outcome (odds ratio, 0.30, 95% confidence interval, 1.00-1.68). However, in our multivariable logistic regression model, gestational age at delivery (odds ratio, 0.93, 95% confidence interval, 0.92-0.94 per day), but not maternal obesity (odds ratio, 1.02, 95% confidence interval, 0.75-1.38), was associated with adverse neonatal outcomes. Obese African American women experienced preterm premature rupture of membranes (189 vs 196 days; p < .001) and delivery (199 vs 205 days; p < .001) earlier than nonobese African American women. This difference was not seen in non-African American women. CONCLUSIONS: Maternal obesity was not associated independently with adverse neonatal outcomes in pregnancies that were affected by preterm premature rupture of membranes after adjustment for gestational age at birth. However, obese African American women rupture and deliver earlier than other women, which causes increased neonatal morbidity.

Delivery of the Obese Gravida.

Obesity in pregnancy confers morbidity to both the mother and neonate. Obese women are at increased risk of cesarean delivery, operative vaginal delivery, and failed trial of labor after cesarean delivery. In addition to impacting the mode of delivery, obesity is associated with hemorrhage, infection, and thromboembolic complications in the peripartum period. The risk of these complications increases with increasing maternal body mass index. In this chapter, we discuss evidence-based strategies to mitigate these risks and to manage complications that occur at the time of delivery in obese parturients.

Do Obese Women Receive the Necessary Interventions to Achieve Vaginal Birth after Cesarean?

Objective We aimed to determine if obese women undergoing trial of labor after cesarean (TOLAC) were more likely to undergo repeat cesarean for arrest disorders prior to active labor, and whether this was due to decreased use of standard interventions to achieve vaginal birth. Study Design This was a secondary analysis of a prospective registry. Women undergoing TOLAC with one prior cesarean and a singleton, term gestation who had a repeat cesarean for an arrest disorder were included. The primary outcome was repeat cesarean prior to active labor (cervical dilation < 6 cm). Obese (body mass index ≥30 kg/m(2)) and nonobese women were compared. Multivariable logistic regression was used to estimate the association between obesity and repeat cesarean prior to active labor. Clinical interventions were compared between groups using t-test and χ (2) test. Results Among 2,098 women undergoing TOLAC, 1,454 (69%) were obese. Obese women were more likely to undergo repeat cesarean for an arrest disorder prior to active labor (odds ratio, 1.4; 95% confidence interval, 1.1-1.7) despite being allowed longer labors and receiving higher maximum doses of oxytocin for a longer duration than nonobese women. Conclusion Obese women were more likely to undergo repeat cesarean prior to active labor despite more clinical interventions to achieve vaginal birth.

Validation of a vaginal birth after cesarean delivery prediction model in women with two prior cesarean deliveries.

OBJECTIVE: To evaluate whether an existing vaginal birth after cesarean delivery (VBAC) prediction model validated for women with one prior cesarean delivery also accurately predicts the likelihood of VBAC in women with two prior cesarean deliveries. METHODS: We performed a secondary analysis of all women attempting trial of labor after cesarean delivery (TOLAC) with a term singleton pregnancy and two prior cesarean deliveries in the Maternal-Fetal Medicine Units Network (MFMU) Cesarean Registry. Probability of VBAC was calculated for each participant using the MFMU VBAC prediction model. Women were considered to have a recurring indication for cesarean delivery if the indication for either their first or second cesarean delivery was arrest of dilation or descent. A receiver operating characteristic curve was used to assess the classification ability of the model and the predicted likelihood of VBAC success was compared with the actual likelihood using a calibration curve. RESULTS: Among 369 women with two prior cesarean deliveries undergoing TOLAC, the actual VBAC rate was 66% (95% confidence interval [CI] 61-71). The mean predicted probability of VBAC was higher among women with a successful TOLAC than those with a failed TOLAC (75% compared with 59%, P<.001). The area under the receiver operating characteristic curve for women with two prior cesarean deliveries was 0.74 (95% CI 0.69-0.80). Within deciles of predicted probability greater than 30%, predicted probabilities were similar to and contained actual probabilities within the 95% CI. CONCLUSION: The estimates of VBAC success based on the MFMU prediction model are similar to the actual rates observed among women with two prior cesarean deliveries.

Reiterative template switching: the effect of single-strand homopolymeric DNA on non-template-directed nucleotide addition by DNA polymerase.

Template switching occurs when DNA polymerase juxtaposes two discontinuous DNA molecules with 3'-terminally complementary ends generated through non-template-directed nucleotide addition. We examined whether juxtaposition of homopolymeric single-stranded oligonucleotides affects non-templated addition. We hypothesized that if DNA polymerase first juxtaposed the two substrates, then the non-template-directed nucleotide addition of any deoxynucleotide would decrease in the presence of its non-complementary template. For dATP, product formation was unaffected by non-complementary substrates. In contrast, dCTP and dGTP incorporation decreased to varying degrees while dTTP incorporation increased in the presence of oligodeoxythymidine but decreased for other non-complementary homopolymers. Interestingly, the presence of complementary templates strongly influenced the formation of highly periodic products indicative of reiterative template switching. Transient template synapsis was observed and found to be dependent on the non-templated sequence added: 3-4 A:T or 1-2 G:C base pairs were needed for stable synapsis, suggesting that base pairing plays a more important role in the active site of the enzyme than previously thought.