Maternal serum placental growth hormone, but not human placental lactogen or insulin growth factor-1, is positively associated with fetal growth in the first half of pregnancy

Abstract

Objective: To investigate if maternal levels of human placental lactogen (hPL), placental growth hormone (PGH) and insulin-like growth factor-1 (IGF-1) are associated with growth rate of the biparietal diameter (BPD) in the first half of pregnancy.

Methods: Data on 8215 singleton fetuses from the Copenhagen First Trimester Study with measurements of BPD from ultrasound scans performed at weeks 11-14 and 17-21 of pregnancy were analyzed. Growth rate was defined as millimeters of growth/day of BPD between the two scans. Fetuses with growth rate below the 2.5(th) centile (low growth rate, n = 203) and above the 97.5(th) centile (high growth rate, n = 203) were identified. As a reference group 212 fetuses with growth rate around the median were identified (intermediate growth rate). Out of the 618 selected cases in the three growth rate groups a total of 463 cases had a blood sample taken at the time of first-trimester ultrasound (5.6% of the original sample size of 8215 pregnancies). The maternal blood serum concentrations of hPL, PGH and IGF-1 were determined in the three different growth-rate groups. Linear regression analysis without adjustment and with adjustment for known and potential confounders was used to compare serum levels between the groups.

Results: Simple linear regression showed a difference in serum level of log(10) PGH between the high and intermediate growth-rate groups (P = 0.037). When adjusted for maternal weight and crown-rump length, multiple linear regression analysis confirmed this difference, as fetuses with high growth rates had a 12% (95% confidence interval, 2-20%; P = 0.009) higher maternal serum level of PGH than those with intermediate growth rates. No differences in hPL and IGF-1 levels between the three different growth-rate groups were found after simple and multiple linear regression analysis.

Conclusion: Maternal PGH levels are higher in women carrying fetuses with high first-trimester growth rates than in controls, both in a simple unadjusted analysis and in analyses adjusted for known and potential confounders. Thus, PGH may be involved in fetal growth regulation as early as in the first trimester of pregnancy.