Fetal heart rate responses to maternal sleep-disordered breathing.

BACKGROUND: Maternal sleep-disordered breathing is associated with adverse pregnancy outcomes and is considered to be deleterious to the developing fetus. Maternal obesity potentiates sleep-disordered breathing, which, in turn, may contribute to the effect of maternal obesity on adverse fetal outcomes. However, only a few empirical studies have evaluated the contemporaneous effects of maternal sleep-disordered breathing events on fetal well-being. These events include apnea and hypopnea with accompanying desaturations in oxyhemoglobin. OBJECTIVE: This study aimed to reconcile contradictory findings on the associations between maternal apnea or hypopnea events and clinical indicators of fetal compromise. It also sought to broaden the knowledge base by examining the fetal heart rate and heart rate variability before, during, and after episodes of maternal apnea or hypopnea. To accomplish this, we employed overnight polysomnography, the gold standard for ascertaining maternal sleep-disordered breathing, and synchronized it with continuous fetal electrocardiography. STUDY DESIGN: A total of 84 pregnant women with obesity (body mass index >30 kg/m2) participated in laboratory-based polysomnography with digitized fetal electrocardiography recordings during or near 36 weeks of gestation. Sleep was recorded, on average, for 7 hours. Decelerations in fetal heart rate were identified. Fetal heart rate and heart rate variability were quantified before, during, and after each apnea or hypopnea event. Event-level intensity (desaturation magnitude, duration, and nadir O2 saturation level) and person-level characteristics based on the full overnight recording (apnea-hypopnea index, mean O2 saturation, and O2 saturation variability) were analyzed as potential moderators using linear mixed effects models. RESULTS: A total of 2936 sleep-disordered breathing events were identified, distributed among all but 2 participants. On average, participants exhibited 8.7 episodes of apnea or hypopnea per hour (mean desaturation duration, 19.1 seconds; mean O2 saturation nadir, 86.6% per episode); nearly half (n=39) of the participants met the criteria for obstructive sleep apnea. Only 45 of 2936 apnea or hypopnea events were followed by decelerations (1.5%). Conversely, most (n=333, 88%) of the 378 observed decelerations, including the prolonged ones, did not follow an apnea or a hypopnea event. Maternal sleep-disordered breathing burden, body mass index, and fetal sex were unrelated to the number of decelerations. Fetal heart rate variability increased during events of maternal apnea or hypopnea but returned to initial levels soon thereafter. There was a dose-response association between the size of the increase in fetal heart rate variability and the maternal apnea-hypopnea index, event duration, and desaturation depth. Longer desaturations were associated with a decreased likelihood of the variability returning to baseline levels after the event. The mean fetal heart rate did not change during episodes of maternal apnea or hypopnea. CONCLUSION: Episodes of maternal sleep apnea and hypopnea did not evoke decelerations in the fetal heart rate despite the predisposing risk factors that accompany maternal obesity. The significance of the modest transitory increase in fetal heart rate variability in response to apnea and hypopnea episodes is not clear but may reflect compensatory, delimited autonomic responses to momentarily adverse conditions. This study found no evidence that episodes of maternal sleep-disordered breathing pose an immediate threat, as reflected in fetal heart rate responses, to the near-term fetus.

Fetal neuromaturation in late gestation is affected by maternal sleep disordered breathing and sleep disruption in pregnant women with obesity.

OBJECTIVE: Maternal sleep disordered breathing and sleep disruption have adverse effects on pregnancy outcomes through multiple potential pathophysiologic pathways. We hypothesize that disordered maternal sleep also adversely impacts the neuromaturation of the fetus. METHODS: Participants in this prospective observational study included 102 obese pregnant women (pre-pregnancy body mass index [BMI] of 30 or higher) at 36 weeks of pregnancy. Fetal neuromaturation, defined through measures of fetal heart rate variability, motor activity, and motor-cardiac coupling, was quantified through digitized fetal actocardiography during an afternoon recording. Maternal sleep measures were collected overnight through polysomnography. Data analysis focused on multiple regression, controlling for maternal BMI, blood pressure, and diabetes. RESULTS: Indicators of higher sleep disordered breathing were associated with delayed fetal neuromaturation and greater fetal motor activity. Less maternal sleep disruption (shorter rapid eye movement [REM] latency, more REM sleep, and/or fewer transitions) was associated with higher fetal heart rate variability and coupling-based neuromaturation. CONCLUSION: Characteristics of disordered maternal sleep affect the developing fetal nervous system. It is unknown whether these results extend to populations that are not characterized by obesity. The influence of maternal sleep on the developing fetal nervous system has been understudied and may yield effects that persist beyond pregnancy.

Fetal heart rate during maternal sleep.

Despite prolonged and cumulative exposure during gestation, little is known about the fetal response to maternal sleep. Eighty-four pregnant women with obesity (based on pre-pregnancy BMI) participated in laboratory-based polysomnography (PSG) with continuous fetal electrocardiogram monitoring at 36 weeks gestation. Multilevel modeling revealed both correspondence and lack of it in maternal and fetal heart rate patterns. Fetal heart rate (fHR) and variability (fHRV), and maternal heart rate (mHR) and variability (mHRV), all declined during the night, with steeper rates of decline prior to 01:00. fHR declined upon maternal sleep onset but was not otherwise associated with maternal sleep stage; fHRV differed during maternal REM and NREM. There was frequent maternal waking after sleep onset (WASO) and fHRV and mHRV were elevated during these episodes. Cross-correlation analyses revealed little temporal coupling between maternal and fetal heart rate, except during WASO, suggesting that any observed associations in maternal and fetal heart rates during sleep are the result of other physiological processes. Implications of the maternal sleep context for the developing fetus are discussed, including the potential consequences of the typical sleep fragmentation that accompanies pregnancy.

Integrating Obstetrical Care and WIC Nutritional Services to Address Maternal Obesity and Postpartum Weight Retention.

OBJECTIVE: This pilot study evaluated a cost neutral, integrated Special Supplemental Nutrition Program for Women Infants and Children (WIC) and obstetrical service model designed to prevent postpartum weight retention in obese women. METHODS: A sample of women who received benefits from the Johns Hopkins (JH) WIC program and prenatal care from the JH Nutrition in Pregnancy Clinic, which provides obstetrical care for women with a BMI ≥ 30 kg/m2, participated in the WICNIP randomized clinical trial. Intervention participants received enhanced nutrition services and education at five visits and during one phone call between delivery and 6 months postpartum. Control participants received standard WIC services. Weight data was collected for all participants at multiple time points: pre-pregnancy, delivery, and postpartum at 4, 6 weeks, 4, and 6 months. Maternal socio-demographic factors, obesity class and the number of education contacts received were also recorded. RESULTS: Fifty-three African-American women were randomized into the intervention and control groups. Intervention participants retained significantly less gestational weight gain than control participants (3.0 ± 11.8 vs. 12.6 ± 20.4, p < 0.05). In both groups, participants with Class III obesity retained significantly less weight than participants in Classes I and II (p = 0.02). CONCLUSIONS FOR PRACTICE: An integrated WIC and obstetrical service model is feasible and can limit postpartum weight retention in obese women. Weight retention at 6 months postpartum between intervention and control participants was statistically significant. Further research should explore targeted interventions by obesity class to address weight retention for low-income, African American women who participate in WIC.

Influence of the 5A's Counseling Strategy on Weight Gain During Pregnancy: An Observational Study.

BACKGROUND: Healthy weight gain during pregnancy may improve health outcomes for women and infants. The objective of this study was to examine providers' use of the 5A's (Assess, Advise, Agree, Assist, and Arrange) in discussions of weight, nutrition, and physical activity during prenatal visits and evaluate the effect of this approach on gestational weight gain. MATERIALS AND METHODS: We studied audio recordings of prenatal visits between 22 obstetrics providers and 120 of their patients, coding visits for providers' use of the 5A's. The relationship between the 5A's and gestational weight gain (total weight gain and excess gestational weight gain) was evaluated using multilevel models to account for patient clustering within provider, and adjusted for prepregnancy body mass index, parent study intervention assignment, gestational age at the study visit, and study visit length. RESULTS: Overall, 55% of prenatal visits included any weight-related behavioral counseling. Of these, 59.1% included one of the 5A's and 40.9% included two or more of the 5A's. Counseling conversations most commonly included Assess or Advise (49% and 85% of counseling conversations, respectively). No recorded visits used all 5A's. In adjusted analyses, patients who received counseling with two or more of the 5A's gained an average of 11.8 fewer pounds than patients who received no counseling (p = 0.001). The odds of excess gestational weight gain were lower among women receiving counseling with at least one of the 5A's (p < 0.05). CONCLUSIONS: The 5A's were associated with lower gestational weight gain and may be a promising counseling strategy to promote healthy weight gain during pregnancy.

Parent and Clinician Perspectives on Sustained Behavior Change after a Prenatal Obesity Program: A Qualitative Study.

BACKGROUND: Infants of obese women are at a high risk for development of obesity. Prenatal interventions targeting gestational weight gain among obese women have not demonstrated consistent benefits for infant growth trajectories. METHODS: To better understand why such programs may not influence infant growth, qualitative semi-structured interviews were conducted with 19 mothers who participated in a prenatal nutrition intervention for women with BMI 30 kg/m2 or greater, and with 19 clinicians (13 pediatric, 6 obstetrical). Interviews were transcribed and coded with themes emerging inductively from the data, using a grounded theory approach. RESULTS: Mothers were interviewed a mean of 18 months postpartum and reported successful postnatal maintenance of behaviors that were relevant to the family food environment (Theme 1). Ambivalence around the importance of postnatal behavior maintenance (Theme 2) and enhanced postnatal healthcare (Theme 3) emerged as explanations for the failure of prenatal interventions to influence child growth. Mothers acknowledged their importance as role models for their children's behavior, but they often believed that body habitus was beyond their control. Though mothers attributed prenatal behavior change, in part, to additional support during pregnancy, clinicians had hesitations about providing children of obese parents with additional services postnatally. Both mothers and clinicians perceived a lack of interest or concern about infant growth during pediatric visits (Theme 4). CONCLUSIONS: Prenatal interventions may better influence childhood growth if paired with improved communication regarding long-term modifiable risks for children. The healthcare community should clarify a package of enhanced preventive services for children with increased risk of developing obesity.

Infant Growth following Maternal Participation in a Gestational Weight Management Intervention.

BACKGROUND: Obesity is widespread and treatment strategies have demonstrated limited success. Changes to obstetrical practice in response to obesity may support obesity prevention by influencing offspring growth trajectories. METHODS: This retrospective cohort study examined growth among infants born to obese mothers who participated in Nutrition in Pregnancy (NIP), a prenatal nutrition intervention at one urban hospital. NIP participants had Medicaid insurance and BMIs of 30 kg/m(2) or greater. We compared NIP infant growth to a historical control cohort, matched on maternal factors: age, race/ethnicity, prepregnancy BMI, parity, and history of prepregnancy hypertension or preterm birth. RESULTS: Growth data were available for 61 NIP and 145 control infants. Most mothers were African American (94%). Mean maternal BMI was 39.9 kg/m(2) (standard deviation [SD], 5.6) for NIP participants and 38.8 kg/m(2) (SD, 6.0) for controls. Pregnancy outcomes, including preterm birth, gestational diabetes, and birth weight, did not differ between groups. NIP participants were more likely to attend a postpartum visit (69% vs. 52%; p value, 0.03). At 1 year, 17% of NIP infants and 15% of controls had weight-for-length (WFL) ≥95th percentile (p value, 0.66). Other markers of accelerated infant growth, including crossing WFL percentiles and peak infant BMI, did not differ between groups. CONCLUSIONS: There was no difference in growth between infants whose mothers participated in a prenatal nutrition intervention and those whose mothers did not. Existing prenatal programs for obese women may be inadequate to prevent pediatric obesity without pediatric collaboration to promote family-centered support beyond pregnancy.

Fetal heart rate and motor development in overweight and obese pregnant women.

OBJECTIVE: To determine the relationship between maternal prepregnancy body mass index (BMI) and fetal cardiac and motor activity and integration during the second half of pregnancy. METHODS: Longitudinal data were collected from 610 nonsmoking women with normally progressing pregnancies at three gestational periods (24, 30-32, and 36 weeks) across eight cohorts studied between 1997 and 2013. Fifty minutes of fetal heart rate and motor activity data were collected at each period via actocardiography in a laboratory setting. Data were digitized and analyzed using customized software. Standard BMI categories were computed from maternal prepregnancy weight and height. Participants were stratified into normal weight (n=401, 65.7%), overweight (n=137, 22.5%), or obese (n=72, 11.8%). RESULTS: Fetuses of obese women showed lower heart rate variability and fewer accelerations relative to fetuses of normal weight women. Fetuses of both obese and overweight women exhibited more vigorous motor activity than fetuses of normal weight women. Cardiac-somatic integration was reduced in both obese and overweight groups. Findings differed by gestational age at assessment. CONCLUSIONS: Excess maternal prepregnancy weight in overweight and obese women alters the normal trajectory of fetal cardiac and motor development and their integration, with effects amplified as pregnancy progresses.

Concurrent levels of maternal salivary cortisol are unrelated to self-reported psychological measures in low-risk pregnant women.

Associations between salivary cortisol and maternal psychological distress and well-being were examined prospectively on 112 women with normally progressing, singleton pregnancies between 24 and 38 weeks gestation. At each of 5 visits, conducted in 3-week intervals, women provided a saliva sample and completed questionnaires measuring trait anxiety, depressive symptoms, pregnancy-specific hassles and uplifts, and psychological well-being. Maternal salivary cortisol was unrelated to psychological measures with the exception of minor associations detected with measures of anxiety and depressive symptoms between 30 and 32 weeks only. Findings indicate that self-reported maternal psychological distress and well-being are not associated with significant variation in maternal salivary cortisol levels during the second half of gestation. This suggests that studies that measure psychological factors in pregnancy but do not measure maternal cortisol should exercise caution in assuming activation of the maternal hypothalamic-pituitary-adrenal axis is the mechanism through which maternal psychological factors are transduced to the fetus.

Associations of maternal psychological factors with umbilical and uterine blood flow.

OBJECTIVE: Alteration to blood flow in the maternal-foetal compartment has been proposed as a mechanism underlying maternal psychological effects on pregnancy outcomes. This study characterised the progression of umbilical and uterine blood flow resistance in healthy pregnancies and evaluated concurrent and longitudinal associations with maternal anxiety and other psychological factors. METHODS: The study assessed participants (n=107) at five visits spanning 24-38 weeks gestation. The resistance index (RI) in the uterine and umbilical arteries was measured with Doppler ultrasound. Maternal psychological function was assessed using validated, self-report instruments. RESULTS: Hierarchical linear modelling revealed that uterine and umbilical RI decreased during the second half of gestation, and that uterine RI was lower in nulliparous women. Few concurrent associations emerged between psychological factors and RI. Longitudinal analyses determined that psychological well-being was associated with decreased left uterine artery RI, and psychological distress was associated with lower right artery RI. CONCLUSIONS: Although uterine artery resistance was modestly associated with the maternal psychological milieu during gestation, our findings do not indicate an association between increased maternal distress and decreased RI. Thus, this study fails to affirm a key component of the hypothesised relation of maternal stress to foetal outcomes via vasoconstriction.

Prenatal antecedents of newborn neurological maturation.

Fetal neurobehavioral development was modeled longitudinally using data collected at weekly intervals from 24 to 38 weeks gestation in a sample of 112 healthy pregnancies. Predictive associations between 3 measures of fetal neurobehavioral functioning and their developmental trajectories to neurological maturation in the first weeks after birth were examined. Prenatal measures included fetal heart rate (FHR) variability, fetal movement, and coupling between fetal motor activity and heart rate patterning; neonatal outcomes include a standard neurologic examination (n = 97) and brainstem auditory evoked potential (BAEP; n = 47). Optimality in newborn motor activity and reflexes was predicted by fetal motor activity, FHR variability, and somatic-cardiac coupling predicted BAEP parameters. Maternal pregnancy-specific psychological stress was associated with accelerated neurologic maturation.

Intrapartum electronic fetal monitoring and the identification of systemic fetal inflammation.

OBJECTIVE: To determine if intrapartum electronic fetal heart rate monitoring (EFM) can identify the fetal in utero systemic inflammatory response or neonatal sepsis, risk factors for the development of brain injury. STUDY DESIGN: This case-control study matched cases with both histologic chorioamnionitis and funisitis (75 preterm and 63 term) to the next delivery without placental or cord inflammation by gestational age and mode of L delivery. The last 2 hours of EFM prior to delivery were reviewed by 3 perinatologists blinded to placental pathology. RESULTS: Preterm and term cases had significantly increased baseline heart rates. Term cases had significant increases in tachycardia, total and late decelerations, and nonreactivity and also had fewer accelerations. EFM parameters had sensitivity of 29-65%, specificity of 46-93%, positive predictive value of 53-80% and negative predictive value of 54-58% in identifying fetal systemic inflammation in this matched, case-control sample. Of the preterm neonates, 9 with sepsis were compared to 141 with negative cultures and were found to have a significant increase in baseline fetal heart rate and tachycardia of longer duration. CONCLUSION: Although significant associations were found, EFM lacks precision in identifying the fetal in utero systemic inflammatory response and neonatal sepsis, predisposing conditions for the development of neonatal encephalopathy.

Cord gas analysis, decision-to-delivery interval, and the 30-minute rule for emergency cesareans.

OBJECTIVE: Our primary objective was to examine the relationship between umbilical arterial gas analysis and decision-to-delivery interval for emergency cesareans performed for nonreassuring fetal status to determine if this would validate the 30-minute rule. STUDY DESIGN: For this retrospective cohort study, all cesarean deliveries performed for nonreassuring fetal status from September 2001 to January 2003 were reviewed. A synopsis of clinical information that would have been available to the clinician at the time of delivery and the last hour of the electronic fetal heart rate tracing prior to delivery were reviewed by three different maternal-fetal medicine specialists masked to outcome, who classified each delivery as either emergent (delivery as soon as possible) or urgent (willing to wait up to 30 minutes for delivery) since immediacy of the fetal condition is the key factor affecting the type of anesthesia used. RESULTS: Of 145 cesareans performed for nonreassuring fetal status during this period, 117 patients met criteria for entry, of which 34 were classified as emergent and 83 as urgent. Kappa correlation was 0.35, showing only fair/moderate agreement between reviewers. In the emergent group, general anesthesia was more common (35.3%, 10.8%, p=0.003), and the decision-to-delivery interval was 14 minutes shorter (23.0+/-15.3, 36.7+/-14.9 minutes, p<0.001). Linear regression showed a statistically significant relationship between increasing decision-to-delivery interval and umbilical arterial pH (r=0.22, p=0.02) and base excess (r=0.33, p<0.001) showing that delivery proceeded sooner for most of those with the worst cord gases, with a gradual improvement over time. For the 13 (11%) neonates with cord gases placing them at increased risk for long-term neurologic sequelae, the decision-to-delivery interval was 24.7+/-14.6 minutes (range 6 to 50 minutes), and 3/13 (23%) were classified as urgent rather than emergent. CONCLUSION: Electronic fetal monitoring shows considerable variation in interpretation among maternal-fetal medicine specialists and is not a sensitive predictor of the fetus developing metabolic acidosis. There is no deterioration in cord gas results after 30 minutes, and most neonates delivered emergently or urgently for nonreassuring fetal status even when born after 30 minutes have normal cord gases. The 30-minute rule is a compromise that reflects the time it takes the fetus to develop severe metabolic acidosis, our imprecision in its identification, and its rarity in the presence of nonreassuring fetal monitoring.