The Effects of Fetal Head Circumference on The Duration of Labor and Cesarean Section in Term Pregnancy

Abstract

Background: To investigate whether fetal head circumference (FHC), independent of estimated fetal weight
(EFW), is a risk factor for prolonged second stage of labor and cesarean delivery in term pregnancy.
Methods: A single-center, non-randomized cross-sectional study including 580 cases was conducted. Cases
included singleton primigravida term pregnancies.
Results: In the vaginal delivery and cesarean groups, the FHC was 35.01 ± 1.18 cm and 35.02 ± 1.32 cm,
respectively (P = 0.95); biparietal diameter (BPD) was 94.99 ± 0.65 mm and 94.96 ± 0.65 mm, respectively (P =
0.66); EFW was 3366.18 ± 207.04 g and 3363.03 ± 251.54 g, respectively (P = 0.34). The lengths of the first and
second stages of labor were not associated with the type of delivery (P₁ = 0.92; P₂ = 0.79). BMI was significantly
associated with the duration of the first stage of labor (P₁ = 0.04), but not the second stage (P₂ = 0.87). BPD was
significantly associated with the duration of the first stage (P₁ = 0.007), but not the second stage (P₂ = 0.57). EFW
was not associated with either stage (P₁ = 0.68; P₂ = 0.73). FHC was significantly correlated with the duration of
the second stage of labor (P < 0.01).
Conclusions: Among various maternal and fetal parameters, FHC was correlated with prolonged second stage
of labor without increasing the risk of cesarean delivery. The decision regarding planned cesarean should not be
based on FHC in uncomplicated pregnancies.