Outcomes of induction of labor with mature and premature amniotic fluid optical density (AFOD): A preliminary case control study
Background: Onset of spontaneous labor occurs on completion of fetal functional maturity at amniotic fluid optical density (AFOD) value 0.98 ± 0.27 (Mean ± SD). All three events occurring together at any time from 35 to 42 weeks indicate individual term for each fetus. Babies born with AFOD ≤0.40 are functionally premature and develop varying degrees of respiratory distress syndrome (RDS). In this study, we tested the hypothesis, labors with AFOD 0.98 ± 0.27 are functionally mature with well‑established labor cascades and may respond well t o induction. On the other hand, labors with AFOD ≤0.40 are functionally premature with poorly established labor cascades and may not respond well t o induction.
Methods: In this gestational age and parity‑matched case control study, cases consisted of 36 uncomplicated singleton laboring women who delivered normally with premature (≤0.40) AFOD values. Controls consisted of 36 similar laboring women who delivered normally with mature AFOD (0.98 ± 0.27) values. Uncentrifuged fresh AF samples collected at amniotomy were used for OD measurement with colorimeter at 650 nm. Women were assigned to groups based on AFOD values. In both groups, labor was induced with vaginal T. Misoprostol 25 mcg 6 hourly up to 4 doses. Labor outcome measures; Bishop score at induction, induction‑ delivery intervals (IDI), induction failures, number of T. Misoprostol required, presence of fetal distress, RDS, and NICU admission days were recorded in both groups and compared.
Results: Median Bishop scores at induction in cases and controls were 5.0 (IQR 4.25‑‑6), 7.0 (IQR 6‑‑8), respectively. Median IDI in cases and controls were 18 h (IQR 12.25‑‑21.5 h) and 7.0 h (IQR 5‑‑9.5 h), respectively. Number of induction failures in cases and controls were 8 and 0, respectively. Outcomes of Induction of labor with…. Statistically significant differences observed in all these outcomes between groups (P = 0.00) favoring inductions with mature AFOD.
Conclusion: Labor induction with mature AFOD value was successful in all women with shorter IDI and with better perinatal outcomes.
Keywords: Induction of labor; mature amniotic fluid optical density; premature amniotic fluid optical density