Longitudinal Study of the Maternal Insulin-Like Growth Factor System before, during and after Pregnancy in Relation to Fetal and Infant Weight

Abstract

Background: The maternal insulin-like growth factor (IGF) system is considered to be involved in fetal growth regulation. However, available data linking this system to fetal growth are contradictory and incomplete. Aims: To measure components of the IGF system before, during and after pregnancy in healthy women and to relate these results, and their changes during pregnancy, to fetal weight (gestational week 31) and birth weight. Methods: Serum concentrations of IGF-I, IGF-II, IGF-binding protein (IGFBP)-1, IGFBP-3 and IGFBP-3 protease activity were assessed in 23 women before conception, at weeks 8, 14, 20, 32 and 35 of pregnancy and 2 weeks postpartum. The data were analyzed using simple and multiple linear regression. Results: One third of the variability in fetal weight was explained by IGF-I in combination with IGFBP-3 protease activity, both assessed at gestational week 32 (p = 0.013). Birth weight was negatively correlated (r = –0.43 to –0.59) with IGFBP-1 at gestational week 20 (p = 0.041), 32 (p = 0.012) and 35 (p = 0.003). Conclusion: We propose there is a finely tuned balance among the components of the IGF system, providing a means for fetal growth regulation.

Body composition of parents and their infants : methodological, anthropometric, metabolic and genetic studies

“…The observed inverse relationship between the serum concentration of IGFBP-1 in the maternal circulation and infant birth weight is in accordance with the two previously conducted studies (28,29) in this area. A new observation from the present study is that IGFBP-1 was related to the FM component of infant weight.…”

An examination of maternal contributors and potential modifiers of fetal growth in pregnancy

“…IGFBP-3 is the most abundant binding protein and carries ~80-90% of the IGFs found in plasma [104,105,108] while IGFBP-1 binds a mere 2% of circulating IGF-I [109]. IGFBP-1 has been cited as a vital down-regulator of IGF bioactivity as levels of IGFBP-1 decrease with increased carbohydrate intake and circulating insulin [110,111]. Cord blood concentrations of IGFBP-3 have been shown to be elevated in neonates born LGA when compared to controls [112].…”

Recent Insights into the Role of the Insulin-Like Growth Factor Axis in Preeclampsia

“…According to a recent longitudinal study, the maternal serum levels of IGF-I remain stable until 20 weeks and then increase whereas IGF-II values do not relatively change throughout gestation [Olausson et al, 2008]. Though in non-pregnant-individuals, IGF-I is primarily derived from the liver, during gestation its main source is decidua under the stimulatory action of a specific growth hormone placental variant (PGH) that is produced by syncytiotrophoblast and extravillous trophoblast from the 7 th or 8 th week of gestation and gradually replaces pituitary growth hormone (GH) in the maternal circulation.…”

“…In particular, IGFBP-1 is increasing rapidly in maternal serum so as to be abundant in second-and third-trimester concomitantly with the second wave of trophoblast invasion until 35 weeks and then decrease thereafter till term [Olausson et al, 2008]. IGFBP-3, the most abundant binding protein for IGFs, provides a circulating storage reservoir for IGFs although its affinity may be decreased in gestation period.…”

“…An endogenous pregnancyrelated serum IGFBP-3 proteolytic activity is considered a fundamental mechanism to increase bioactive IGFs [Lewitt et al, 1998]. Conflicting results have been reported regarding IGFBP-3 concentration throughout pregnancy probably as a result of different applied measurement methods; a recent longitudinal study reported that the maternal serum levels of IGFBP-3 remained stable and increased only after 35 weeks of gestation [Olausson et al, 2008]. The exact impact of IGFBPs also depends on the posttranslational modification of the protein (e.g.…”