BACKGROUND AND PURPOSE:

• Blankenship et al. (AJOG, 2019) evaluated first stage labor progress for large for gestational age (LGA) infants

METHODS:

• Retrospective cohort study (2004 to 2014)
• Participants
  • Term | Vertex | Singleton
  • Reached 10-cm cervical dilation
• Definitions
  • LGA: Birthweight >90th percentile for gestational age
  • AGA: Birthweight 10th to 90th percentile for gestational age
  • First stage of labor: >3 cm cervical dilation
• Study design and data analysis
  • Labor curves were constructed: Compared between LGA and AGA
  • Median duration of labor after 3-cm cervical dilation stratified by
    • Actual infant birthweight | Parity | Labor onset (e.g., spontaneous, augmentation, induction) | Pregestational DM or GDM | BMI
  • Data on pelvic shape, fetal position, and uterine infection not available
  • Multivariate analysis adjusted for confounding factors

RESULTS:

• 17,097 women included
  • AGA: 92.7%
  • LGA: 7.3%
    • Nulliparous: 30.9%
    • Induction: 37.0%
    • Obese: 68.8%
    • Pregestational DM or  GDM: 12.6%
• LGA: Slower progression from 3- to 10-cm cervical dilation  (P<0.01)
  • LGA: Median, 8.57 hours (5th, 95th percentile, 2.95, 24.86)
  • AGA: 6.46 hours (5th, 95th percentile, 2.23, 18.74)
• LGA: Dilation from 6–10 cm progressed slower in
  • Nulliparous compared with multiparous women (P<0.01)
    • Nulliparous: 3.28 hours (5th, 95th percentile, 0.71, 15.16)
    • Multiparous: 2.03 hours (5th, 95th percentile, 0.44, 9.39)
  • Obese compared with not obese women (P<0.01)
    • Obese: 2.36 hours (5th, 95th percentile, 0.51, 10.91)
    • Not obese: 1.79 hours (5th, 95th percentile, 0.39, 8.31)
• Labor curves did not differ between LGA and AGA for the following
  • Labor onset (nonaugmented spontaneous labor vs induced labor)
  • Pregestational DM or gestational diabetes mellitus

CONCLUSION:

• Authors acknowledge study limitations including that study can address associations and not causality
• Women with LGA infants take longer to reach the second stage of labor vs AGA
  • The difference greatest in nulliparous and obese women once in the active phase of labor (6-10 cm)
• Labor onset and the presence of diabetes or gestational diabetes do not seem to affect the duration of the first stage of labor after 3-cm cervical dilation
• Authors suggest based on data in this study
  • Obesity results in delay through stage 1 because greater adipose tissue deposits in the pelvis and weaker contractions
  • Metabolic DM effects seem less likely to alter labor curve patterns
• Authors recommend further studies that will incorporate the following
  • Use EFW to identify macrosomia “…because this would provide greater clinical insight into anticipated labor progression, influence prospective labor management in cases of suspected fetal macrosomia, and enable comparison with our labor curves that were constructed from postnatal infant birthweight”

Learn More – Primary Sources:

First stage of labor progression in women with large-for-gestational age infants

Related ObG Topics:

Macrosomia: Determination of EFW and Recommendations for Delivery

Are Large-for-Gestational Age Pregnancies at an Increased Risk of Stillbirth?

Does Early Accelerated Fetal Growth Increase the Risk for LGA and Macrosomia?

Universal Ultrasound Screening for Fetal Macrosomia: Is It Cost-Effective?