BACKGROUND AND PURPOSE:

• Majority of studies on large-for-gestational-age (LGA) and macrosomia have focused on relationship with maternal diabetes and maternal weight
• Common assumptions include biological variation in growth early in pregnancy being more limited and of less consequence than later in pregnancy
• Simic et al. (Acta Obstet Gynecol Scand, 2017) examined whether accelerated fetal growth in early pregnancy was associated with risk of severe LGA and macrosomia at birth

METHODS:

• Low-risk population cohort study
• Population: Women with non-anomalous singleton pregnancies without history of diabetes or hypertension
• Exposure: Growth discrepancy at early second-trimester ultrasound expressed in days
• Discrepancy in growth: Defined as the difference in days between fetal age estimated by early second-trimester scan and expected gestational age based on the first-trimester scan
• Gestational age calculated using fetal biparietal diameter (BPD) in both first and second trimester using and Selbing and Kjessler formula (gestational age = 58.65 + [1.07 x BPD] + (0.0138 x BPD²)
• LGA: Birthweight for gestational age according to gestational age and fetal sex, > 97th centile
• Macrosomia: birthweight ≥4500 g at term (≥ 37 weeks)
• Multivariable logistic regression was used to estimate the link between accelerated growth in first trimester through early second trimester and LGA and macrosomia at birth
  • Odds ratio (OR) adjusted for maternal age, body mass index, height, parity, in vitro fertilization, smoking, and country of birth
  • Restricted analyses were performed in groups without gestational diabetes and with normal body mass index

RESULTS:

• 68,771 pregnancies were eligible for the study
• Compared with fetuses with a discrepancy of no more than 2 days at early second-trimester ultrasound, fetuses with ≥7-day discrepancy had an increased risk for severe LGA
  • Adjusted OR 1.80 (95% CI 1.23–2.64)
  • In pregnancies limited to those without GDM, OR 1.78 (95% CI 1.2-2.64)
• Compared with fetuses with a discrepancy of no more than 2 days at early second-trimester ultrasound, fetuses with ≥7-day discrepancy had an increased risk for macrosomia
  • Adjusted OR 2.15 (95% CI 1.55-2.98)
  • In pregnancies limited to those without GDM, OR 2.12 (1.54-2.95)

CONCLUSION:

• In low-risk population, ultrasound-estimated accelerated fetal growth in second trimester was associated with an 80% increased risk of severe LGA and over double the risk for a macrosomic infant
• The authors conclude that accelerated fetal growth early in pregnancy is a risk factor for LGA and macrosomia in women in a low risk population and can be used to identify at-risk pregnancies early on

Learn More – Primary Sources:

Accelerated fetal growth in early pregnancy and risk of severe large- for- gestational-age and macrosomic infant: a cohort study in a low-risk population

Related ObG Topics:

Can Abdominal Circumference Alone Be Used to Predict SGA or LGA Newborns?

Is There an Association Between High or Low Weight Gain and Maternal and Infant Outcomes?

Macrosomia: Determination of EFW and Recommendations for Delivery