Analysis of incidence and risk factors of preterm birth in 15 urban hospitals in China / 中华围产医学杂志

ABSTRACT

Objective To investigate the incidence and major risk factors of preterm birth in urban hospitals in China so as to provide evidence for effective interventions to reduce preterm birth.Methods Postpartum women delivered between 22 and 37 weeks of gestation were selected from 15 urban hospitals in Beijing,and Guangdong,Hu'nan,Hubei,Sichuan and Shaan'xi Province.Between April 2012 and March 2013,data of 10 days were collected every 3 months.Questionnaire was obtained under informed consent from 9 143 cases,including 958 cases of preterm birth and 8 185 cases of term birth.Demographics,history of pregnancy,prenatal care,and incidences of complication and/or comorbidities,lifestyle and dietary habit during pregnancy were included in the questionnaire.Chi-square test for univariate analysis and logistic regression multivariate analysis were used for statistics.Results The incidence ofpreterm birth was 9.9％(10 986/111 095) in the 15 hospitals.Among the 958 preterm birth cases,2.3％(22/958) were in gestational weeks ＜28,22.7％(217/958) in ≥ 28-＜34 gestational weeks,and 75.1％(719/958) in ≥ 34-＜37 gestational weeks.Univariate analysis showed that the influencing factors related to preterm birth included(preterm birth groups vs term birth group)maternal age ＞40 years or ＜18 years[1.6％(15/958) vs 1.2％(100/8 185),0.6％(6/958) vs 0.1％(7/8 185),22=18.515,P=0.000],ethnic Han [97.7％(919/941) vs 96.3％(7 811/8 115),22=4.819,P=0.028],less educated (lower than junior middle school) [27.1％(257/950) vs 14.9％(1 215/8 132),22=91.879,P=0.000],unmarried status[2.8％(27/955) vs 1.3％(110/8 154),22=12.609,P=0.000],family income ＜5 000 yuan(RMB)/ month [40.5％(380/939) vs 30.8％(2 479/8 060),22=40.457,P=0.000],being preterm born [14.2％(134/942) vs 2.6％(211/8 099),22=349.801,P=0.000],adverse obstetric history [12.9％(72/958) vs 8.5％(346/8 185),22=12.009,P=0.001],previous preterm delivery [50.0％(36/72) vs 17.1％(59/346),x2=36.840,P=0.000],fetal malformation history[4.2％(3/72) vs 18.8％(65/346),22=9.351,P=0.002],reproductive technology assisted conception [7.7％(72/930) vs 2.1％(172/8 037),x22=98.816,P=0.000],antenatal visits ＜5 times [21.0％(195/930) vs 12.0％(966/8 037),22=68.634,P=0.000],second hand smoking [24.5％(235/958) vs 19.6％(1 603/8 185),x2=13.573,P=0.000],unpleasant events during pregnancy [27.6％(264/958) vs 22.0％(1 802/8 185),x2=15.213,P=0.000],folic acid supplementation before and during pregnancy [before pregnancy39.1％(375/958) vs 49.0％(4 007/8 185);during pregnancy61.2％(586/958) vs 67.0％(5 485/8 185),x2=31.842,11.667,P=0.000,0.001],multivitamin supplementation during pregnancy [43.4％(416/958) vs 48.1％(3 937/8 185),x2=7.393,P=0.007],and pregnant complications,including anemia,premature rupture of membranes,intrauterine infection,pregnancy complication heart diseases,oligohydramnios,placental abruption,placental previa,fetal distress,multiple gestation,etc [59.9％(574/958) vs 38.9％(3 184/8 185),x2=156.47l,P=0.000].Logistic regression multivariate analysis showed that the following factors were significantly associated with preterm birthantenatal visits ＜5 times (OR=1.916,95％CI1.060-3.462),intrauterine infection (OR=5.441,95％CI1.723-17.176),severe preeclampsia during pregnancy (OR=11.220,95％CI1.041-2.149),premature rupture of membranes (OR=3.188,95％CI1.916-5.305) and placenta previa (OR=6.607,95％CI2.919-14.801).Conclusions There are multiple factors for preterm birth in urban hospitals in east-northern part of China,and quality of antenatal care should be improved and pregnant complications should be closely monitored and managed timely.