pn Perinatology Perinatology 2508-4887 2508-4895 The Korean Society of Perinatology 10.14734/PN.2018.29.04.147 pn-29-147 Original Article Pregnancy and Neonatal Outcomes of Group B Streptococcus Infection in Preterm Births LeeYae HeunMD 1 LeeYoo JungMD 1 JungSun YoungMD 1 KimSuk YoungMD 1 SonDong WooMD 2 SeoIl HyeMD 3 Departments of Obstetric Gynecology, Gachon University College of Medicine, Incheon, Korea Departments of Pediatrics, Gachon University College of Medicine, Incheon, Korea Departments of Clinical Pathology, Gachon University College of Medicine, Incheon, Korea Correspondence to Suk Young Kim, MD Department of Obstetric Gynecology, Gachon University Gil Medical Center, Gachon University College of Medicine, 21 Namdong-daero 774beon-gil, Namdong-gu, Incheon 21565, Korea Tel: +82-32-460-3254 Fax: +82-32-460-3290 E-mail: ksyob@gilhospital.com 012018 19012018 294147 152 20032018 25042018 08082018 Copyright © 2018 The Korean Society of Perinatology 2018 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Objective

This study examines whether maternal group B Streptococcus (Streptococcus agalactiae, GBS) infection was associated with preterm births and premature neonatal outcomes.

 Methods

Maternal and neonatal outcomes were examined among singleton pregnant women with preterm birth (from 24+0 weeks to 36+6 weeks) who were tested for GBS (n=203) during the pregnancy. Data were collected retrospectively from the medical records of women who delivered at our hospital from January 2015 to February 2017. We compared obstetrical factors (causes of preterm birth) and neonatal (gestational age at delivery, birth weight, Apgar score 1 min/5 min, hospitalization period, duration of mechanical ventilation, neonatal C-reactive protein within three days, and other complication [respiratory distress syndrome, neonatal deaths]) outcomes between GBS-infected and non-infected pregnant women.

 Results

There were 203 singleton pregnant women included in the study, 25 of whom were confirmed to have a GBS infection during the pregnancy. There was no difference in neonatal outcomes by GBS status. Preterm premature rupture of membranes (pPROM), as an obstetric factor, was associated with GBS infection (P=0.022). GBS infection raised the risk of pPROM by 3.6 times (odds ratio 3.648, 95% confidence interval 1.476-9.016, P=0.005).

 Conclusion

GBS infection in preterm birth was associated with pPROM but did not result in adverse neonatal outcomes. Continuous attention and evaluation of GBS infection, a major cause of neonatal sepsis and pneumonia, are needed.

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Study Subject Characteristics (n=203)

  GBS (+) (n=25, 12.3%) GBS (−) (n=178, 87.7%) P-value
Maternal age (years) 32.6±4.6 33.0±4.9 0.300∗
STD infection (%) 4 (9.5) 38 (90.5) 0.610†
Chorioamnionitis (%) 8 (15.1) 45 (84.9) 0.675†
Maternal CRP 1.21±2.65 1.31±3.09 0.389∗
Maternal WBC 11,125±3,581 10,923±3,581 0.445∗

Values are presented as mean±standard deviation or number (%). Abbreviations: GBS, group B Streptococcus agalactiae; STD, sexually transmitted disease; CRP, C-reactive protein; WBC, white blood cell.

Mann-Whitney test.

Chi-squared test.

Obstetric Factors between GBS (+) and GBS (-) in Preterm Birth

  GBS (+) (n=25, 12.3%) GBS (−) (n=178, 87.7%) P-value∗
Causes of preterm birth (%)
SPTL 2 (8.0) 64 (36.0) 0.005
pPROM 14 (56.0) 54 (30.3) 0.022
IIOC 1 (4.0) 6 (3.4) 1.000
Maternal complications† 7 (28.0) 44 (24.7) 0.806
Fetal complications‡ 1 (4.0) 10 (5.6) 1.000

Values are presented as mean±standard deviation or number (%). Abbreviations: GBS, group B Streptococcus agalactiae; SPTL, spontaneous preterm labor; pPROM, preterm premature rupture of membrane; IIOC, incompetent internal os of cervix.

Chi-squared test.

Maternal complications: pregnancy-induced hypertension, preeclampsia, placenta previa, placental abruption, uterine rupture.

Fetal complications: fetal distress, fetal growth restriction, fetal anomaly.

Neonatal Outcomes between GBS (+) and GBS (−) in Preterm Birth

  GBS (+) (n=25, 12.3%) GBS (−) (n=178, 87.7%) P-value
Gestational age at delivery (weeks) 32.7±3.3 32.3±3.3 0.154∗
Birth weight (g) 2,126±851 1,894±676 0.114∗
Apgar score 1 minute 7.6±1.7 7.6±1.9 0.295∗
Apgar score 5 minutes 9.0±1.1 9.0±1.4 0.273∗
Hospitalization period (days) 32.8±40.5 32.7±40.0 0.412∗
Duration of mechanical ventilation (days) 15.6±33.1 13.9±29.9 0.494∗
Neonatal CRP within three days 0.40±0.82 0.25±0.57 0.094∗
RDS (%) 7 (11.7) 53 (88.3) 1.000†
Neonatal deaths (%) 1 (12.5) 7 (87.5) 1.000†

Values are presented as mean±standard deviation or number (%). Abbreviations: GBS, group B Streptococcus agalactiae; CRP, C-reactive protein; RDS, respiratory distress syndrome.

Mann-Whitney test.

Chi-squared test.

Logistic Regression-Derived ORs and 95% CIs for the Association between GBS and pPROM

  Univariate Multivariate
OR (95% CI) P-value OR (95% CI) P-value
Gestational age at delivery 1.020 (1.005-1.034) 0.007 0.987 (0.962-1.014) 0.353
Birth weight 1.001 (1.000-1.001) <0.001 1.001 (1.000-1.002) 0.002
GBS infection 2.923 (1.247-6.851) 0.014 3.648 (1.476-9.016) 0.005

Abbreviations: GBS, group B Streptococcus agalactiae; pPROM, preterm premature rupture of membrane; OR, odds ratio; Cl, confidence interval.