Perinatal outcome and amniotic fluid index in the antepartum and intrapartum periods: A meta-analysis,☆☆

https://doi.org/10.1016/S0002-9378(99)70393-5Get rights and content

Abstract

Objective: Our purpose was to perform a meta-analysis of studies on the risks of cesarean delivery for fetal distress, 5-minute Apgar score <7, and umbilical arterial pH <7.00 in patients with antepartum or intrapartum amniotic fluid index >5.0 or <5.0 cm. Study Design: Using a MEDLINE search, we reviewed all studies published between 1987 and 1997 that correlated antepartum or intrapartum amniotic fluid index with adverse peripartum outcomes. The inclusion criteria were studies in English that associated at least one of the selected adverse outcomes with an amniotic fluid index of ≤5.0 cm versus >5.0 cm. Contingency tables were constructed for each study, and relative risks and standard errors of their logs were calculated. Fixed–effects pooled relative risks were calculated for groups of studies that were homogeneous, whereas random-effects pooled relative risks were calculated for significantly heterogeneous groups of studies. Results: Eighteen reports describing 10,551 patients met our inclusion criteria. An antepartum amniotic fluid index of ≤5.0 cm, in comparison with >5.0 cm, is associated with an increased risk of cesarean delivery for fetal distress (pooled relative risk, 2.2; 95% confidence interval, 1.5-3.4) and an Apgar score of <7 at 5 minutes (pooled relative risk, 5.2; 95% confidence interval, 2.4-11.3). An intrapartum amniotic fluid index of ≤5.0 cm is also associated with an increased risk of cesarean delivery for fetal distress (pooled relative risk, 1.7; 95% confidence interval, 1.1-2.6) and an Apgar score <7 at 5 minutes (pooled relative risk, 1.8; 95% confidence interval, 1.2-2.7). A poor correlation between the amniotic fluid index and neonatal acidosis was noted in the only study that examined this end point. More than 23,000 patients are necessary to demonstrate that the incidence of umbilical arterial pH <7.00 is 1.5 times higher among those with oligohydramnios in labor than among those with adequate amniotic fluid index (α = 0.05; β = 0.2) Conclusions: An antepartum or intrapartum amniotic fluid index of ≤5.0 cm is associated with a significantly increased risk of cesarean delivery for fetal distress and a low Apgar score at 5 minutes. There are few reports linking amniotic fluid index and neonatal acidosis, the only objective assessment of fetal well-being. A multicenter study with sufficient power should be undertaken to demonstrate that a low amniotic fluid index is associated with an umbilical arterial pH <7.00. (Am J Obstet Gynecol 1999;181:1473-8.)

Section snippets

Material and methods

A MEDLINE search was conducted for all English-language publications involving human subjects with the key words or phrases being amniotic fluid index, oligohydramnios, and amniotic fluid . The search was limited to the years 1987-1997, since the index publication by Phelan et al,3 which introduced the concept of AFI in 1987. Other inclusion criteria for the studies considered in the meta-analysis were (1) publication in a peer-reviewed journal, (2) determination of AFI by the technique of

Results

Eight publications5, 9, 15, 16, 17, 20, 21, 22 examined the relationship of antepartum AFI to peripartum outcome. Four of these reports5, 15, 20, 22 involved high-risk patients for whom antepartum surveillance was indicated; 3 reports focused on patients with a single complication (diabetic pregnancy,17 severe preeclampsia at <34 weeks’ gestation,9 or gestational age of ≥41 weeks21); and 1 study16 included patients between 37 and 42 weeks’ gestation with intact membranes but did not specify the

Comment

In term pregnancies oligohydramnios, defined by an ultrasonographic determination of AFI ≤5.0 cm, has been suggested as an indication for delivery.14, 15, 18 Ten years after Phelan et al3 described the semiquantitative method of determining the AFI, it is reasonable to reassess the evidence to support the criterion of an AFI ≤5.0 cm as a clinical cutoff point for intervention. Our meta-analysis showed that the use of the AFI for clinical decision making is problematic.

First, the incidence of

References (28)

  • A Golan et al.

    Oligohydramnios: maternal complications and fetal outcome in 145 cases

    Gynecol Obstet Invest

    (1994)
  • JP Phelan et al.

    Amniotic fluid volume assessment with the four-quadrant technique at 36-42 weeks’ gestation

    J Reprod Med

    (1987)
  • American College of Obstetricians and Gynecologists

    Ultrasonography in pregnancy

    (1993)
  • SE Rutherford et al.

    The four-quadrant assessment of amniotic fluid volume: an adjunct to antepartum fetal heart rate testing

    Obstet Gynecol

    (1987)
  • Cited by (180)

    • Diagnosis and surveillance of late-onset fetal growth restriction

      2018, American Journal of Obstetrics and Gynecology
      Citation Excerpt :

      In a prospective series of pregnancies with oligohydramnios and FGR,111 the fetal growth centile remained stable over the 8 weeks following the diagnosis, suggesting that the oligohydramnios is not reflecting any risk of progression. Furthermore, a meta-analysis112 of 18 trials showed an association with abnormal 5-minute Apgar, but not with acidosis or perinatal death in SGA (RR, 1.6; 95% CI, 0.9–2.6). Because of the limited evidence, the inclusion of oligohydramnios assessment in management protocols of SGA/FGR is not recommended.

    • Isolated oligohydramnios and long-term neurological morbidity of the offspring

      2020, Journal of Developmental Origins of Health and Disease
    View all citing articles on Scopus

    Reprint requests: Suneet P. Chauhan, MD, Division of Maternal-Fetal Medicine, Regional Women’s Health Care, 853 North Church St, Suite 403, Spartanburg, SC 29303.

    ☆☆

    0002-9378/99 $8.00 + 06/1/101831

    View full text