Risk factors of late preterm birth and perinatal complications among late preterm infant / 中华围产医学杂志

ABSTRACT

To analyze maternal and neonatal complications among late preterm birth cases and to investigate risk factors of late preterm birth. Methods This was a retrospective analysis of 258 late preterm cases (late preterm group) born in Peking University First Hospital from January 1, 2009 to December 31, 2010. Maternal comorbidity and complications, delivery modes, and neonatal complications of these 258 late preterm infants were compared with 308 term cases (term group) during the same period. Statistical analysis was performed usingχ2 test, Fisher's exact probability test, t test and logistic regression. Results In Peking University First Hospital, late preterm births accounted for 3.9%(258/6 695) of live births and 60.1%(258/429) of preterm births. The incidence of the following maternal complications among the late preterm group was higher than that among term group(all P<0.05) severe pre-eclampsia [7.4%(19/258) vs 1.0%(3/308), χ2=15.35]; preterm rupture of membrane [42.6%(110/258) vs 15.3%(47/308), χ2=52.49];cervical insufficiency [1.9%(5/258) vs 0.0%(0/308), Fisher's exact test];placenta previa[3.5%(9/258) vs 0.6%(2/308), Fisher's exact test] and placental abruption [2.7%(7/258) vs 0.3%(1/308), Fisher's exact test]. Severe pre-eclampsia was the major risk factor leading to late preterm birth. The incidence of the following neonatal complications among the late preterm group was higher than that among term group (all P<0.05)respiratory distress syndrome (NRDS) [11.6%(30/258) vs 1.6%(5/308), χ2=24.22]; hyperbilirubinemia [64.3%(166/258) vs 39.6%(122/308),χ2=34.36];electrolyte disturbance [12.8%(33/258) vs 1.6(95/308),χ2=27.96];hypothermia [7.0%(18/258) vs 2.9%(9/308),χ2=5.08];infectious pneumonia[13.6%(35/258) vs 3.2%(10/308), χ2=20.43]; leukoencephalopathy [3.1%(8/258) vs 0.3%(1/308), χ2=5.25]; low body temperature [18.6%(48/258) vs 3.6%(11/308),χ2=33.98] and neonatal asphyxia [6.2%(16/258) vs 1.0%(3/308),χ2=11.86]. The incidence of the following neonatal complications among late preterm infants born at<35 weeks gestation was higher than that among late preterm infants born at≥35 weeks gestation (all P<0.05)NRDS [30.4%(14/46) vs 7.5%(16/212) ,χ2=19.26];hyperbilirubinemia [91.3%(42/46) vs 58.5%(124/212), χ2=17.74]; electrolyte disturbance [21.7%(10/46) vs 10.8%(23/212), χ2=4.02]; intracranial hemorrhage [8.7%(4/46) vs 1.9%(4/212),χ2=3.88];leukoencephalopathy [10.9%(5/46) vs 1.4%(3/212),χ2=8.32] and neonatal asphyxia [15.2%(7/46) vs 4.2%(9/212), χ2=6.05]. Conclusions Severe pre-eclampsia is the major risk factor leading to late preterm birth. The incidence of complications among late preterm infants is higher than that among term infants. If a pregnancy has to be terminated because of maternal disorders, the pregnancy period should be extended to 35 weeks if it permits.