Timing of Planned Cesarean Delivery by Racial Group

Caesarean section and respiratory system disorders in newborns

Cesarean section (C-section) delivery is associated with a higher risk of respiratory problems in newborns, particularly if performed electively at 37 weeks. This risk is greater than with spontaneous or induced labor but diminishes as gestation advances. To lower the incidence of respiratory issues in newborns, it is vital to promote natural labor, avoid unnecessary C-sections, and offer thorough prenatal care. Healthcare providers and expectant mothers should assess the risks and benefits of elective C-sections carefully. By advocating for natural labor and reducing unnecessary C-sections, the occurrence of respiratory problems in newborns can be decreased. Adequate prenatal care and monitoring are crucial for identifying and managing potential risk factors for respiratory diseases in newborns. It is crucial for healthcare professionals to educate expectant mothers about the risks of elective C-sections and the advantages of allowing labor to progress naturally. By fostering transparent communication and collaborative decision-making between healthcare providers and pregnant women, well-informed choices can be made that prioritize the health of both the mother and the baby. Furthermore, ongoing research and advancements in medical technology can improve our understanding of how delivery methods affect newborn respiratory health, ultimately leading to better outcomes and care practices in the future.

Timing of Elective Cesarean Section and Neonatal Outcomes in Term Singleton Deliveries: A Single-Center Experience

OBJECTIVE

This study aimed to evaluate the timing of elective cesarean sections at 37 to 41 weeks from a tertiary hospital in Japan. The primary outcome was the rate of adverse neonatal outcomes, especially focusing on neonates delivered at 38 weeks of gestation.

STUDY DESIGN

The study population was drawn from singleton pregnancies delivered following planned cesarean birth at the Fukuda Hospital from 2012 to 2019. Information on deliveries was obtained from the hospital database, which contains clinical, administrative, laboratory, and operating room databases.

RESULTS

After excluding women with chronic conditions, maternal complications, indications for multiple births, or a neonate with an anomaly, 2,208 neonates remained in the analysis. Among adverse neonatal outcomes, the rate was significantly higher in neonates delivered at 37 weeks of gestation (unadjusted odds ratio [OR] = 13.22 [95% confidence interval [CI]: 6.28, 27.86], p < 0.001) or 38 weeks of gestation (unadjusted OR = 1.82 [95% CI: 1.04, 3.19], p = 0.036) compared with neonates delivered at 39 to 41 weeks. The adjusted risk of any adverse outcome was significantly higher at 380-1/7 weeks (adjusted OR = 2.40 [95% CI: 1.35, 4.30], p = 0.003) and 382-3/7 weeks (adjusted OR = 1.89 [95% CI: 1.04, 3.44], p = 0.038) compared with neonates delivered at 39 to 41 weeks, respectively.

CONCLUSION

Our findings suggest that elective cesarean sections might be best scheduled at 39 weeks or later. When considering a cesarean at 38 weeks, it appears that 384/7 weeks of gestation or later could be a preferable timing in the context of reducing neonatal risks. However, as the composite outcome includes mostly minor conditions, the clinical significance of this finding needs to be carefully interpreted.

KEY POINTS

· Timing of elective cesarean sections from 37 to 41 weeks was evaluated in a Japanese tertiary hospital.. · Neonates delivered at 37 and 38 weeks had higher adverse outcome rates compared with 39 to 41 weeks.. · Scheduling elective cesarean sections at least 384/7 weeks or later may reduce neonatal risk..

Antenatal Corticosteroids to Asian Women Prior to Elective Cesarean Section at Early Term and Effects on Neonatal Respiratory Outcomes

This exploratory study aimed to evaluate the effects of antenatal corticosteroids in singleton pregnancies of Asian women prior to elective cesarean section (CS) at early term on neonatal respiratory outcomes.

METHODS

This is a pilot and pragmatic randomized trial conducted at a university hospital in Malaysia. Women with singleton pregnancies planned for elective CS between 37+0 and 38+6 weeks gestation were randomly allocated into the intervention group, where they received two doses of IM dexamethasone 12 mg of 12 h apart, 24 h prior to surgery OR into the standard care, control group, and both groups received the normal routine antenatal care. The primary outcome measures were neonatal respiratory illnesses, NICU admission and length of stay.

RESULTS

A total of 189 patients were recruited, 93 women in the intervention group and 96 as controls. Between the steroid and control groups, the mean gestation at CS was similar, 266.1 ± 3.2 days (38 weeks) vs. 265.8 ± 4.0 days (37+6 weeks), p = 0.53. The mean birthweight of infants was 3.06 ± 0.41 kg vs. 3.04 ± 0.37 kg, p = 0.71. Infants with respiratory morbidities were primarily due to transient tachypnea of newborn (9.7% vs. 6.3%), and congenital pneumonia (1.1% vs. 3.1%) but none had respiratory distress syndrome. Only four infants required NICU admission (2.2% vs. 3.1%, p = 0.63). Their average length of stay was not statistically different; 3.5 ± 2.1 days vs. 5.7 ± 1.5 days, p = 0.27.

CONCLUSIONS

Elective CS at early term before 39 weeks was associated with a modest overall incidence of neonatal respiratory illness (10.1%) in this Asian population. Antenatal dexamethasone did not diminish infants needing respiratory support, NICU admission and length of stay.

Optimal timing of elective repeat cesarean deliveries of term singleton pregnancies: A multicenter cross-sectional study

OBJECTIVE

Cesarean deliveries must be optimally timed to minimize their effects on mothers and neonates. This study aimed to determine the optimal timing of elective repeat cesarean deliveries to reduce the incidence of neonatal respiratory disorders and of emergent cesarean deliveries.

MATERIALS AND METHODS

This multi-center, cross-sectional, retrospective analysis evaluated data on the maternal and neonatal outcomes of 856 singleton pregnancies scheduled for elective repeat cesarean deliveries at 37-39 weeks' gestation. The emergent cesarean delivery and neonatal respiratory disorder risks were analyzed according to the scheduled cesarean delivery times.

RESULTS

The elective cesarean delivery rates were 91.0% during the first and 92.6% during the second half of the 37th week of gestation, 88.7% during the first and 82.9% during the second half of the 38th week of gestation, and 62.5% during the first and 33.3% during the second half of the 39th week of gestation. The neonatal respiratory disorder rates were 21.8% for elective cesarean deliveries during the first half of the 37th week of gestation and approximately 8% for elective cesarean deliveries during the second half of the 37th week until the first half of the 38th week of gestation. No neonatal respiratory disorders occurred among the babies delivered by elective cesarean deliveries during the 39th week of gestation.

CONCLUSION

For improved maternal and neonatal outcomes in the Asian population, it may be better to perform scheduled elective repeat cesarean deliveries from the second half of the 37th week of gestation until the 38th week of gestation following confirmation of gestational age by early first trimester ultrasonography.

Maternal characteristics and neonatal outcomes of emergency repeat caesarean deliveries due to early-term spontaneous labour onset

BACKGROUND

The optimal timing of elective repeat caesarean delivery has yet to be determined. One of the reasons to schedule an elective repeat caesarean delivery before 39 weeks gestation is to avoid emergency caesarean delivery due to spontaneous onset of labour.

AIMS

By ascertaining maternal characteristics and neonatal outcomes associated with early-term onset of spontaneous labour, we aim to determine the optimal timing for each individual repeat caesarean delivery.

MATERIALS AND METHODS

We performed a retrospective analysis of women with repeat caesarean deliveries planned at 38 weeks gestation between 2005 and 2019 at a tertiary referral hospital in Japan. A multivariate logistic regression analysis was adopted to identify independent contributing factors for early-term spontaneous labour onset. We also compared the rate of neonatal adverse events between women who underwent emergency repeat caesarean deliveries due to the onset of early-term labour and the ones who underwent elective repeat caesarean deliveries at 38 weeks.

RESULTS

We included 1152 women. History of vaginal deliveries (adjusted odds ratio (AOR), 2.12; 95% confidence interval (95% CI), 1.21-3.74), history of preterm deliveries (AOR, 2.28; 95% CI, 1.38-3.77), and inadequate maternal weight gain during pregnancy (AOR, 1.78; 95% CI, 1.15-2.75) significantly increased the risk of early-term spontaneous labour onset. In terms of occurrence rate of neonatal complications, we found no significant difference between the groups.

CONCLUSION

These maternal factors are significant predictors for early-term labour onset of repeat caesarean deliveries. The onset of early-term labour did not increase the likelihood of neonatal complications.

A systematic review and time-response meta-analysis of the optimal timing of elective caesarean sections for best maternal and neonatal health outcomes

BACKGROUND

The rate of caesarean sections (CS) has increased in the last decades to about 30% of births in high income countries. Many CSs are electively planned without an urgent medical reason for mother or child. An early CS though may harm the newborn. Our aim was to evaluate the gestational time point after the 37 + 0 week of gestation (WG) (after prematurity = term) of performing an elective CS with the lowest morbidity for mother and child by assessing the time course from 37 + 0 to 42+ 6 WG.

METHODS

We performed a systematic literature search in MEDLINE, EMBASE, CENTRAL and CINAHL in November 2018. We included studies that compared different time points of elective CS at term no matter the reason for elective CS. Our primary outcomes were the rate of admissions to the neonatal intensive care unit (NICU), neonatal death and maternal death in early versus late term elective CS. Various binary and dose response random effects meta-analyses were performed.

RESULTS

We identified 35 studies including 982,749 women. Except one randomised controlled trial, all studies were cohort studies. We performed a linear time-response meta-analysis on the primary outcome NICU admission on 14 studies resulting in a decrease of the relative risk (RR) to 0.63 (95% CI 0.56, 0.71) from 37 + 0 to 39 + 6 WG. RR for neonatal death showed a decrease to 39 + (0-6) WG (RR 0.59 95% CI 0.43 to 0.83) and increase from then on (RR 2.09 95% CI 1.18 to 3.70) assuming a U-shape course and using a cubic spline model for meta-analysis of four studies. We only identified one study analyzing maternal death resulting in RR of 0.38 (95% CI 0.04 to 3.40) for 37 + 0 + 38 + 6 WG versus ≥39 + 0 WG.

CONCLUSION

Our systematic review showed that elective CS (primary and repeated) before the 39 + 0 WG lead to more NICU admissions and neonatal deaths, although death is rare and increases again after 39 + 6 WG. We did not find enough evidence on maternal outcomes. There is a need for more research, considering maternal outcomes to provide a balanced decision between neonatal and maternal health.

SYSTEMATIC REVIEW REGISTRATION

Registered in PROSPERO (CRD42017078231).

The role of three-dimensional ultrasonography fetal lung volume measurement in the prediction of neonatal respiratory function outcome

BACKGROUND

Respiratory distress is commonly encountered among premature babies immediately after birth resulting in significant neonatal morbidity or mortality.

OBJECTIVES

To evaluate the possible correlation between three dimensional fetal lung volumes (FLVs) and neonatal respiratory outcomes.

STUDY DESIGN

A cohort study included 100 pregnant women who participated in the study and were divided into two groups; group A (n: 50 - women pregnant ±34-37 weeks) and group B (n: 50 - women pregnant ±37⁺¹ to 40 weeks). A three dimensional measurement of the right fetal lung was made using virtual organ computer-aided analysis (VOCAL) software then correlated to neonatal respiratory functions namely Apgar score at birth and the occurrence of respiratory distress syndrome (RDS).

RESULTS

In group A, FLV was negatively correlated with Apgar score and the occurrence of RDS. In group B, FLV showed no statistical correlation with Apgar score and the occurrence of RDS.

CONCLUSIONS

Three dimensional fetal lung volumes might be an accurate noninvasive predictor for the development of RDS among preterm fetuses.

Differences in meconium stained amniotic fluid in an Australian population: A retrospective study

BACKGROUND

Meconium stained amniotic fluid commonly occurs postdates ( >40 weeks gestation) indicating fetal maturity. Previous literature indicates that different ethnicities mature at different rates.

AIM

To compare the rate of meconium stained amniotic fluid of Australian-born and non-Australian born women.

METHODS

A retrospective correlation study design was implemented, using data collected in the birth outcomes system at one tertiary hospital. Data was collected from all women who gave birth to a term (>/=37 weeks gestation), singleton, liveborn baby between January 1st to December 31st, 2014. Maternal country of birth was used for comparison. Categorical data was analyzed using Chi-Square test for Independence. Continuous variables were assessed for normality, and differences were compared using an Independent t-test or a Mann-Whitney U test. All tests were two-tailed and p<0.05 was considered statistically significant.

RESULTS

3,041 women were included; 1131 Australian-born and 1910 non-Australian born. Meconium stained amniotic fluid occurred more frequently in non-Australian born women compared to Australian-born women (23.5% vs. 19.8 p=0.02). Their babies were significantly smaller (Mean=3265g, Standard Deviation 463.8 vs Mean=3442g, Standard Deviation 499.2, p<0.001), with no difference in gestational length (Mean=39.4, Standard Deviation 1.28 vs Mean=39.5, Standard Deviation 1.18, p=0.06). Increasing gestational age had the strongest association with meconium stained amniotic fluid; >/=42 weeks gestation occurring 3.52 (95% Confidence Interval: 2.00, 6.22, p=<0.001) more than <40 weeks gestation.

CONCLUSION

Maternity health services should record ethnicity and region of birth to provide individualised care as women born overseas often have poorer perinatal outcomes when compared to Australian-born women.

'Elective caesarean section at 38-39 weeks gestation compared to > 39 weeks on neonatal outcomes: a prospective cohort study

Background

This study was conducted to compare neonatal complications in scheduled cesarean sections (CS) between 38 and 39 gestational weeks with CS performed after 39 gestational weeks in Iranian low -risk pregnant women.

Methods

In this cohort study, 2086 patients were enrolled based on the inclusion and exclusion criteria. The neonates were evaluated in terms of the following items: transient tachypnea of the newborn (TTN), respiratory distress syndrome (RDS), sepsis, need for NICU hospitalization, birth weight, birth height, head circumference, and the first minute and fifth minute Apgar score. Several multiple logistic regression models were performed for each response variable (adverse outcome) separately.

Results

The incidence of NICU admission was significantly higher in neonates born at 38–39 gestational weeks than those who were born after 39 gestational weeks. No significant differences were found in the incidence of neonatal sepsis, TTN, and RDS between the two groups.

Conclusion

According to our study results, elective CS at 38–9 weeks’ gestation is associated with a higher rate of TTN and NICU admission in comparison with elective CS performed after 39 completed gestational weeks.

Optimal timing for elective caesarean delivery in a Chinese population: a large hospital-based retrospective cohort study in Shanghai

OBJECTIVE

To assess the relationship between the timing of antepartum elective caesarean delivery (CD) at term and perinatal outcomes in a Chinese population.

METHODS

We conducted a retrospective cohort study of mode of delivery at a large obstetric centre in Shanghai, China between 2007 and 2014. Eligibility criteria included: term nulliparous women with a singleton gestation undergoing antepartum elective CD.

RESULTS

There were 19 939 women delivered by antepartum CD without indications, with 5.9% performed at 37-37 6/7 weeks, 36.2% at 38-38 6/7 weeks, 38.4% at 39-39 6/7 weeks, 15.4% at 40-40 6/7 weeks, 4.0% at ≥41 weeks. As compared with births at 39-39 6/7 weeks, births at 37 weeks were associated with an increased odds of neonatal respiratory disease (adjusted odds ratian(aOR): 4.82; 95% CI 3.35 to 6.94), neonatal infection (aOR: 3.68; 95% CI 1.80 to 7.52), hypoglycaemia (aOR: 3.85; 95%CI 2.29 to 6.48), hyperbilirubinaemia (aOR: 3.50; 95%CI 2.12 to 5.68), neonatal intensive care admission (aOR: 3.73; 95% CI 2.84 to 4.89) and prolonged hospitalisation (aOR: 7.51; 95% CI 5.10 to 11.07). Births at 38 weeks, 40 weeks or ≥41 weeks were also associated with an increased odds of neonatal respiratory disease with corresponding aORs (95% CI) of 2.26 (1.71 to 3.00), 1.97 (1.33 to 2.94) and 2.91 (1.80 to 4.70), respectively.

CONCLUSION

For women undergoing elective CD, neonatal outcome data suggest that delivery at 39-39 6/7 complete weeks is optimal timing in a Chinese population.

Timing of elective cesarean delivery at term and its impact on maternal and neonatal outcomes among Thai and other Southeast Asian pregnant women

AIM

The impact of timing of elective cesarean delivery (CD) at term on maternal and neonatal outcomes among Thai and other Southeast Asian pregnancies was investigated. The rate of spontaneous labor before the scheduled CD, as well as maternal characteristics predicting spontaneous labor, was also evaluated.

METHODS

Data on maternal and neonatal outcomes of 1221 singleton pregnancies scheduled for either an elective repeat CD or an elective primary CD at 37-40 weeks of gestation were studied. The association between maternal characteristics and the risk of spontaneous labor was evaluated by univariate and multivariate analyses.

RESULTS

There were no significant differences in severe maternal complications between performing an elective CD at 39 weeks and at the other gestational ages. Severe neonatal complications were significantly decreased when a CD was performed electively from 38 weeks onwards. A total of 503 women (41.2 %) went into spontaneous labor before the scheduled CD. Using 39 weeks as the reference group, scheduling a CD at 37 or 38 weeks decreased the risk of spontaneous labor (6.67-fold and 4.55-fold, respectively) while scheduling a CD at 40 weeks had a 2.54-fold increased risk. A history of previous CD and teenage pregnancy were also predictors of spontaneous labor; adjusted odds ratios were 14.27 and 3.93, respectively.

CONCLUSION

The timing of elective CD at term had impacts on pregnancy outcomes among Thai and other Southeast Asian women. Gestational age at scheduled CD, a previous CD and teenage pregnancy were predictors of spontaneous labor.

Cesarean delivery on maternal request in China: what are the risks and benefits?

OBJECTIVE

The purpose of this study was to describe the risks and benefits of cesarean delivery on maternal request (CDMR) in a Chinese population.

STUDY DESIGN

A retrospective cohort study of mode of delivery was conducted at the largest obstetric center in Shanghai, China, from 2007-2013. Eligibility criteria included singleton term nulliparous women with vertex presentation; women with major fetal anomalies or stillbirth before labor were excluded.

RESULTS

A total of 66,226 women were included in the analysis: 40,560 women (61.2%) had planned vaginal birth, with 32,833 spontaneous vaginal deliveries (80.9%), 4990 intrapartum CDs (12.3%), and 2737 assisted vaginal deliveries (6.7%). A total of 16,333 women (24.7%) underwent CDMR. We observed no significant difference between the CDMR and planned vaginal delivery groups in the frequencies of maternal intensive care unit admission (0.2% vs 0.2%), severe postpartum hemorrhage (0.5% vs 0.5%), maternal infection (1.3% vs 1.3%), organ injuries (0.4‰ vs 0.5‰), and thromboembolic disorders (0.1‰ vs 0.1‰). The perinatal mortality rate was similar in the 2 groups (0.4‰ vs 0.6‰; adjusted odds ratio, 0.51; 95% confidence interval, 0.20-1.30; P = .159). The frequencies of birth trauma (0.2‰ vs 1.1‰), neonatal infection (0.4% vs 0.7%), hypoxic ischemic encephalopathy (0.4‰ vs 1.8‰), and meconium aspiration syndrome (0.2‰ vs 0.6‰) were lower; the frequency of respiratory-distress syndrome (0.6% vs 0.4%) was higher in the CDMR group.

CONCLUSION

Compared with nulliparous women who tried vaginal delivery, women who underwent CDMR had similar short-term maternal outcomes with some neonatal benefit.

Racial disparities in the optimal for induction of labor in low-risk term pregnancies: a national population-based study

OBJECTIVE

The recommendation for elective induction of labor (IOL) is to await ≥ 39 weeks. Studies show earlier maturity of Blacks compared to Whites. The objective was to examine the effect of the Black race on the risk of intrapartum and neonatal complications after IOL.

METHODS

Black women with non-indicated IOL at 37-42 weeks were selected from the CDC-Birth Cohorts 2007-2010. Congenital anomalies, hypertension/diabetes, low-birth weight, breech presentation, previous cesarean and premature rupture of membranes were excluded. Intrapartum/neonatal complications were analyzed. Logistic regression was used to calculate adjusted odds ratios, using 39 weeks as reference.

RESULTS

311,264 black were compared with 2,451,774 deliveries of other races. For Blacks, the risks of cesarean delivery and intrapartum complications were lower at 38 weeks. Chance of vaginal delivery was greater at 38 weeks. Risks of neonatal complications was not increased at 38 compared to 39 weeks.

CONCLUSIONS

Intrapartum complications were lower at 38 than at 39 weeks in Blacks with no increased risk of neonatal complications. Meconium staining and fetal distress were higher as early as at 40 weeks, perhaps due to accelerated maturation. While a 39-week goal is simple and benefits many patients, a more "personalized medicine" approach may benefit even more mothers and babies.

Pregnancy, parturition and preeclampsia in women of African ancestry

Maternal and associated neonatal mortality rates in sub-Saharan Africa remain unacceptably high. In Mulago Hospital (Kampala, Uganda), 2 major causes of maternal death are preeclampsia and obstructed labor and their complications, conditions occurring at the extremes of the birthweight spectrum, a situation encapsulated as the obstetric dilemma. We have questioned whether the prevalence of these disorders occurs more frequently in indigenous African women and those with African ancestry elsewhere in the world by reviewing available literature. We conclude that these women are at greater risk of preeclampsia than other racial groups. At least part of this susceptibility seems independent of socioeconomic status and likely is due to biological or genetic factors. Evidence for a genetic contribution to preeclampsia is discussed. We go on to propose that the obstetric dilemma in humans is responsible for this situation and discuss how parturition and birthweight are subject to stabilizing selection. Other data we present also suggest that there are particularly strong evolutionary selective pressures operating during pregnancy and delivery in Africans. There is much greater genetic diversity and less linkage disequilibrium in Africa, and the genes responsible for regulating birthweight and placentation may therefore be easier to define than in non-African cohorts. Inclusion of African women into research on preeclampsia is an essential component in tackling this major disparity of maternal health.

Randomised trial of planned caesarean section prior to versus after 39 weeks: unscheduled deliveries and facility logistics--a secondary analysis

Objectives

To compare the impact of scheduling caesarean section prior to versus after 39 completed weeks of gestation on the occurrence of unscheduled caesarean section and rescheduling of the procedure.

Methods

Secondary analysis from a multicentre randomised open-label trial including singleton pregnant women with a healthy foetus and a reliable due date. Women were allocated by computerized telephone randomisation to planned caesarean section at 38 weeks and three days or 39 weeks and three days. The outcomes were unscheduled deliveries with provided reasons, such as spontaneous labour onset or supervening complications, and any changes in the scheduled delivery date. Statistical analyses were according to intention-to-treat using Fisher’s exact test.

Results

From March 2009 to June 2011 1,274 women were included. Median difference in gestational age at delivery was six days. Compared to the 38 weeks group, the women in the 39 weeks group were more likely to have an unscheduled caesarean section (15.2% vs. 9.3%; RR 1.64, 95% CI 1.21; 2.22), to deliver between 6 pm and 8 am (10 % vs. 6%; RR 1.68, 95% CI 1.14; 2.47), or to have the procedure rescheduled (36.7% vs. 23%; RR 1.6, 95% CI 1.34;1.90).

Conclusions

Scheduling caesarean section after 39 weeks leads to a 60% increase in unscheduled caesarean sections and a 70% increase in delivery outside regular work hours as compared to scheduling of the procedure prior to 39 weeks.

Trial Registration

www.clinicaltrials.gov NCT00835003 http://www.clinicaltrials.gov/ct2/show/NCT00835003?term=NCT00835003&rank=1

Late better than early elective term Cesarean section

AIM

  Caesarean section (CS) deliveries have increased, mostly because of patient/obstetrician preference. Although CS decreases the risk of delivery-related injuries, it increases the risk for respiratory and neurological complications. Complication rates are reportedly higher for elective CSs for term infants performed at 37-38 gestational weeks than later. We investigated this difference in an Israeli cohort.

METHODS

  Data on all births in our medical centre during 2007-2009 were reviewed. Those on elective CSs for term infants were retrieved and divided into 'early' (37-38 gestational weeks) or 'late' (week 39 or later) groups whose epidemiological and outcome characteristics were compared.

RESULT

  Of the 12,276 births, 596 were early and 454 were late elective CSs. There were no differences in gender, ethnicity, Apgar score or length of hospital stay. Twenty-six infants from the early group and 11 infants from the late group were transferred to the neonatal intensive care unit. Within them, compared with all elective CSs, the morbidity rate was higher for the former infants than for the latter.

CONCLUSION

  Morbidity was higher among infants who were delivered at 37-38 gestational weeks by elective CS. We recommend postponing elective CSs to ≥39 weeks.

Increased risk for respiratory distress among white, male, late preterm and term infants

OBJECTIVE

To determine whether race/ethnicity and sex independently increase risk of respiratory distress syndrome (RDS) in late preterm and term infants.

STUDY DESIGN

Using a cohort design, we studied the risk of RDS associated with race/ethnicity and sex in infants with gestational age (GA) 34 to 42 weeks born between 1 January 2000 and 31 December 2009 (n=286 454) within 12 hospitals in the Northern California Kaiser Permanente Medical Care Program.

RESULT

Male sex (adjusted odds ratio (aOR) 1.68; 95% confidence interval 1.45 to 1.93) and White race/ethnicity (vs Asians (aOR 0.57; 95% confidence interval 0.47 to 0.70), Blacks (aOR 0.66; 95% confidence interval 0.50 to 0.87), and Hispanics (aOR 0.76; 95% confidence interval 0.64 to 0.90)) independently increase risk for RDS regardless of GA. A GA <39 weeks, operative delivery, maternal diabetes, and chorioamnionitis also increased RDS risk in this cohort.

CONCLUSION

Male sex and White race/ethnicity independently increase risk for RDS in late preterm and term infants. Timing of elective delivery should acknowledge these risks.

Maternal and fetal characteristics associated with meconium-stained amniotic fluid

OBJECTIVE

To estimate the rates of meconium-stained amniotic fluid (AF) and adverse outcome in relation to gestational age and racial group, and to investigate the predictors of meconium-stained AF.

METHODS

We studied 499,096 singleton births weighing at least 500 g, at 24 or more weeks of gestation, from 1988 to 2000. The predictors of meconium-stained AF from 37 weeks of gestation onward were determined using multiple logistic regression.

RESULTS

The crude meconium-stained AF rates in preterm, term, and postterm births were 5.1% (95% confidence interval [CI] 4.9-5.4), 16.5% (95% CI 16.4-16.6), and 27.1% (95% CI 26.5-27.6), respectively; the rates in blacks, South Asians, and whites were 22.6% (95% CI 22.2-23.1), 16.8% (95% CI 16.5-17.1), and 15.7% (95% CI 15.6-15.8), respectively. Independent predictors of meconium-stained AF included being black (odds ratio [OR] 8.4, 95% CI 2.4-28.8), vaginal breech delivery (OR 4.7, 95% CI 4.2-5.3), being South Asian (OR 3.3, 95% CI 1.3-8.3), and being in an advancing week of gestation (OR 1.39, 95% CI 1.38-1.40). More blacks (17.9%, 95% CI 17.3-18.4) and South Asians (11.8%, 95% CI 11.5-12.1) with good outcome and no risk factors for fetal hypoxia had meconium-stained AF than did whites (11.2%, 95% CI 11.1-11.4). Using white neonates born at 40 weeks as reference, the absolute risk of adverse outcome at 41 and 42 weeks were 2% and 5% in whites, 3% and 7%, in South Asians, and 7% and 11% in blacks.

CONCLUSION

Meconium-stained AF rates are different among races and across gestational age, and overall risk of adverse outcomes in meconium stained AF is low.

LEVEL OF EVIDENCE

II.

Characteristics Associated With Intending and Achieving a Planned Home Birth in the United Kingdom: An Observational Study of 515,777 Maternities in the North West Thames Region, 1988–2000

BACKGROUND AND OBJECTIVES: This study aims to identify factors that have an independent association with planned home birth. It investigates the social, demographic, and obstetric profile of those who choose home birth as compared with those choosing hospital birth. This crucial evidence is lacking in the U.K. context and is needed when comparing pregnancy outcomes of different birth settings. Otherwise, the comparison is problematic because observed differences in incidence of pregnancy outcomes may be due to the fact that different types of women choose different birth settings. It is important to understand these differences in order to control for them.

METHOD: This is an observational study involving secondary analysis of computerized maternity records from 15 hospitals in the former North West Thames Regional Health Authority (RHA) area. All pregnancies that resulted in a live or stillbirth in the years 1988–2000 are included (N = 515,777). Two binary logistic regression models are used: one with intended place of birth at booking as the outcome and the other with actual place of birth as the outcome.

RESULTS: Women who are parous, White European, aged 30 and older, living in a relatively affluent area, and partnered are most likely to intend a home birth. Among those who intend a home birth at the end of pregnancy, predictors of achieving a home birth include an uncomplicated and relatively short labor, being parous, a low-risk pregnancy, and being White European. The hospital providing maternity care predicts the outcome for both models.

CONCLUSIONS: Key variables robustly predict an intention to deliver at home and the achievement of a planned home birth. Studies comparing the outcomes of different birth settings in the United Kingdom should control for these variables.

The genetic susceptibility to respiratory distress syndrome

Previous studies to identify a genetic component to RDS have shown conflicting results. Our objectives were to evaluate and quantify the genetic contribution to RDS using data that comprehensively includes known environmental factors in a large sample of premature twins. Data from a retrospective chart review of twins born at < or =32 wk GA were obtained from two neonatal units. Mixed effects logistic regression (MELR) analysis was used to assess the influence of several independent covariates on RDS. A zygosity analysis, including the effects of additive genetic, common environmental and residual effects (ACE) factors, was performed to estimate the genetic contribution. Results reveal that the 332 twin pairs had a mean GA of 29.5 wk and birth weight (BW) of 1372 g. An MELR identified significant nongenetic covariates as male gender (p = 0.04), BW (p < 0.001), 5-min Apgar score (p < 0.001), and treating institution (p = 0.001) as significant predictors for RDS. The ACE model was used to estimate the genetic susceptibility to RDS by adjusting for the above factors. We found 49.7% (p = 0.04) of the variance in liability to RDS was the result of genetic factors alone. We conclude that there is a significant genetic susceptibility to RDS in preterm infants.

The effect of exclusion of cases with unrecorded best estimate of gestational age on the estimates of preterm birth rate

OBJECTIVES

To investigate the effect of excluding cases with unrecorded best estimate of gestational age at birth on pregnancy outcome reporting and to determine the reasons for unrecorded gestational age data.

DESIGN

Prospective study.

SETTING

Fifteen maternity units in North West London.

POPULATION

497,105 women who booked for antenatal care from 1988 to 1998.

METHOD

Multiple logistic regression analysis.

MAIN OUTCOME MEASURES

Preterm birth rate of, and the factors associated with, cases with unrecorded best estimate of gestational age at birth.

RESULTS

Of the 53,981 cases with an unrecorded best estimate of gestational age at birth, by using additional data, it was possible to compute a new best estimate of gestational age in 80%. In this latter group, the preterm birth rate was 42% (95% CI 41.5-42.6). The corrected, overall preterm birth rate in North West London (9.8%, 9.7-9.9) was higher than the original estimate (7.6%, 7.5-7.7), which included only cases with recorded data on gestational age at birth. The most significant factors associated with an unrecorded gestational age were no ultrasound scan (OR 49, P < 0.001), and preterm birth <31 weeks (OR 30, P < 0.001).

CONCLUSIONS

The incidence of preterm birth are likely to be under-reported in studies where only cases with readily available gestational age data are included. In routinely collected maternity data, human omission is an important contributing factor for an unrecorded best estimate of gestational age at birth. This is associated with the urgent transfer of babies to the neonatal intensive care unit.