Objective
To compare the annual incidence rates of caesarean delivery between induction of labour and expectant management in the setting of macrosomia.
Design
This is a retrospective cohort study.
Setting
Deliveries in the USA in 2003.
Population
Singleton births of macrosomic neonates to low-risk nulliparous women at 39 weeks of gestation and beyond.
Methods
Women who had induction of labour at 39 weeks of gestation with a neonatal birthweight of 4000 ± 125 g (3875–4125 g) were compared with women who delivered (either induced or spontaneous labour) at 40, 41 or 42 weeks (i.e. expectant management), assuming an intrauterine fetal weight gain of 200 g per additional week of gestation. Similar comparisons were made at 40 and 41 weeks of gestation. Chi-square test and multivariable logistic regression analysis were used for statistical comparison.
Main outcome measures
Method of delivery, 5-minute Apgar scores, neonatal injury.
Results
There were 132 112 women meeting the study criteria. In women whose labours were induced at 39 weeks and who delivered a neonate with a birthweight of 4000 ± 125 g, the frequency of caesarean was lower compared with women who delivered at a later gestational age (35.2% versus 40.9%; adjusted OR 1.25, 95% CI 1.17–1.33). This trend was maintained at both 40 weeks (36.1% versus 42.6%; adjusted OR 1.31, 95% CI 1.23–1.40) and 41 weeks (38.9% versus 41.8%; adjusted OR 1.16, 95% CI 1.06–1.28) of gestation.
Conclusions
In the setting of known birthweight, it appears that induction of labour may reduce the risk of caesarean delivery. Future research should concentrate on clinical and radiological methods to better estimate birthweight to facilitate improved clinical care. These findings deserve examination in a large, prospective, randomised trial.
Objective
To estimate the risk of short-term complications in neonates born between 34 and 36 weeks by week of gestation.
Design
This is a retrospective cohort study.
Setting
Deliveries in 2005 in the United States of America.
Population
Singleton live births between 34 and 40 weeks gestational age.
Methods
Gestational age was subgrouped into 34, 35, 36 and 37–40 completed weeks. Statistical comparisons were performed using chi-square test and multivariable logistic regression models, with 37–40 weeks gestational age designated as referent.
Main Outcome Measures
Perinatal morbidities, including 5-minute Apgar scores, hyaline membrane disease, neonatal sepsis/antibiotics use, and admission to the intensive care unit.
Results
There were 175,112 neonates born between 34 and 36 weeks in 2005. Compared to neonates born between 37 and 40 weeks, neonates born at 34 weeks had higher odds of 5-minute Apgar<7 (adjusted odds ratio [aOR]=5.51, 95% CI [5.16–5.88]), hyaline membranes disease (aOR=10.2 [9.44–10.9]), mechanical ventilation use >6 hours (aOR=9.78 [8.99–10.6]) and antibiotics use (aOR=9.00 [8.43–9.60]). Neonates born at 35 weeks were similarly at risk of morbidity, with higher odds of 5-minute Apgar <7 (aOR 3.42 [3.23–3.63], surfactant use (aOR 3.74 [3.21–4.22], ventilation use >6 hours (aOR 5.53 [5.11–5.99] and NICU admission (aOR 11.3 [11.0–11.7). Further, neonates born at 36 weeks remain at higher risk of morbidity compared to deliveries at 37–40 weeks.
Conclusions
While the risk of undesirable neonatal outcomes decreases with increasing gestational age, the risk of neonatal complications in late preterm births remains higher compared to infants delivered at 37–40 weeks gestation.
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