CORRELATION AMONG AMNIOTIC FLUID INDEX (AFI), CESAREAN SECTION RATE, AND LABOR LENGTH IN INDUCTED PREGNANCIES BEYOND 41 WEEKS' GESTATION WITH UNFAVORABLE CERVIX

ABSTRACT

This paper evaluated how the pregnancy after 41 completed weeks' gestation with amniotic fluid index (AFI) > 6 has a slower response to the prostaglandin E₂ (PGE₂) induction. Eighty-one post-term pregnancies (41 completed gestations' weeks) with unfavorable cervix were considered in this follow-up. Induction was performed by means of intracervical PGE₂ gel (Dinoprostone 0.5 mg). After 12 hours, if the cervix was still unfavorable, then another gel administration followed. Cases that had oxytocin administration were excluded from the study. The median time of spontaneous delivery in the overall series was 25 hours, 14 minutes. We had 18 cases of cesarean section (22.2%). In the group of pregnancies with AFI > 6 (60 cases) and in the group with AFI ≤ 6 (21 cases), the median time of spontaneous delivery was 29 hours, 25 minutes and 23 hours, 39 minutes, respectively (p-value = 0.02). The rate of cesarean sections was 26.67 and 9.52, respectively in the two groups (p-value > 0.05). Two out of four cases of cesarean sections for fetal distress belonged to the group of AFI > 6. All the 14 cases of cesarean section for dystocia belonged to the group with AFI > 6. Considering just patients who did not deliver within 12 hours (57 cases), median time of spontaneous delivery was 33 hours and 24 hours 40 minutes for group AFI > 6 (42 cases) and AFI ≤ 6 (15 cases), respectively (p-value = 0.0009). Thirty-one cases out of 57 had another PGE₂ gel administration. Adjusted odds ratio was 0.33 (0.16-0.65, 95% C.I.) for AFI ≤ 6 versus AFI > 6.

KEYWORD

Post-term pregnancy - amniotic fluid index - Kaplan-Meier algorithm - Cox algorithm

REFERENCES

• 1 Beisher N A, Evans J H, Townsend L. Studies in prolonged pregnancy. I. The incidence of prolonged pregnancy.  Am J Obstet Gynecol . 1969;  103 476-482
• 2 Miller D A, Paul R H. Postterm pregnancy. In: Reece EA, Hobbins JC, eds. Medicine of the Fetus & Mother 2nd ed. Vol. 87. Philadelphia: Lippincott-Raven 1999: 1627-1639
• 3 Shime J, Gare D J, Andrews J, Bertrand M, Salgado J, Whillans G. Prolonged pregnancy: surveillance of the fetus and the neonate and the course of labor and delivery.  Am J Obstet Gynecol . 1984;  148 547-552
• 4 Eden R D, Seifert L S, Winegar A, Spellacy W N. Maternal risk status and postdate pregnancy outcome.  J Reprod Med . 1988;  33 53-57
• 5 The National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Units. A clinical trial of induction of labor versus expectant management in postterm pregnancy.  Am J Obstet Gynecol . 1994;  170 716-723
• 6 Gibb D M, Cardozo L D, Studd J W, Cooper D J. Prolonged pregnancy: is induction of labour indicated?.  <~>A prospective study. Br J Obstet Gynaecol . 1982;  89 292-295
• 7 Katz Z, Yemini M, Lancet M, Mogilner B M, Ben-Hur H, Caspi B. Nonaggressive management of post-date pregnancies.  Eur J Obstet Gynecol Reprod Biol . 1983;  15 71-79
• 8 Cardozo L, Fysh J, Pearce J M. Prolonged pregnancy: the management debate.  Br Med J (Clin Res Ed) . 1986;  293 1059-1063
• 9 Dyson D C, Miller P D, Armstrong M A. Management of prolonged pregnancy: induction of labor versus antepartum fetal testing.  Am J Obstet Gynecol . 1987;  156 928-934
• 10 Augensen K, Bergsjo P, Eikeland T, Askvik K, Carlsen J. Randomised comparison of early versus late induction of labour in post-term pregnancy.  Br Med J (Clin Res Ed) . 1987;  294 1192-1195
• 11 Witter F R, Weitz C M. A randomized trial of induction at 42 weeks gestation versus expectant management for postdates pregnancies.  Am J Perinatol . 1987;  4 206-211
• 12 Bergsjo P, Huang G D, Yu S Q, Gao Z Z, Bakketeig L S. Comparison of induced versus non-induced labor in post-term pregnancy: a randomized prospective study.  Acta Obstet Gynecol Scand . 1989;  68 683-687
• 13 Martin Jr N J, Sessums J K, Howard P, Martin R W, Morrison J C. Alternative approaches to the management of gravidas with prolonged-postterm-postdate pregnancies.  J Miss State Med Assoc . 1989;  30 105-111
• 14 Hannah M E, Hannah W J, Hellmann J, Hewson S, Milner R, Willan A. Induction of labor as compared with serial antenatal monitoring in post-term pregnancy: a randomized controlled trial. The Canadian Multicenter Post-term Pregnancy Trial Group.  N Engl J Med . 1992;  326 1587-1592
• 15 Divon M Y, Marks A D, Henderson C E. Longitudinal measurement of amniotic fluid index in postterm pregnancies and its association with fetal outcome.  Am J Obstet Gynecol . 1995;  172 142-146
• 16 Lawrence S, Rosenfeld C R. Fetal pulmonary development and abnormalities of amniotic fluid volume.  Semin Perinatol . 1986;  10 142-153
• 17 Shmoys S M, Sivkin M, Dery C, Monheit A G, Baker D A. Amniotic fluid index: an appropriate predictor of perinatal outcome.  Am J Perinatol . 1990;  7 266-269
• 18 Rath W. Prolonged pregnancy-prostaglandins as the cause of labor onset.  Z Geburtshilfe Perinatol . 1994;  198 207-214