Insulin-like Growth Factors-I and -II and Insulin-like Growth Factor Binding Protein-1 during normal pregnancy: pattern of secretion and correlation with other placental hormones

OBJECTIVES

To describe pattern of secretion of insulin-like growth factor (IGF)-I, IGF-II, IGF binding protein (IGFBP)-1 and their correlation with each other and major placental hormones during normal pregnancy.

DESIGN

Longitudinal study.

SETTING

Academic Institutions and a Tertiary Care Maternity Hospital.

PARTICIPANTS

Healthy women with singleton uncomplicated pregnancies (N = 35).

MEASUREMENTS

Serum levels of IGF-I, IGF-II, IGFBP-1, chorionic gonadotrophin (HCG), placental lactogen (HPL), prolactin, oestradiol and progesterone were studied thrice during the antenatal period and within 24 h of delivery.

RESULTS

IGF-I, IGFBP-1, HPL, prolactin, oestradiol and progesterone increased and HCG decreased significantly with advancing gestation (Repeated measures ANOVA: P < 0.01 to 0.0001). IGF-II levels were not significantly affected by period of gestation. Significant negative correlations (multiple regression analysis) were seen between IGFBP-1 and prolactin at 28 +/- 2 (P = 0.0226) and 36 +/- 2 (P = 0.0417) weeks of amenorrhoea (WOA) and between oestradiol and IGF-II at 36 +/- 2 WOA (P = 0.037). Prolactin and IGF-I at 14 +/- 2 WOA (P = 0.0225) and progesterone and IGFBP-1 at 28 +/- 2 WOA (P = 0.0216) correlated positively.

CONCLUSIONS

Maternal IGF-I and IGFBP-1 but not IGF-II significantly increase as pregnancy advances. Components of the IGF system regulate or are affected by some of the placental hormones and the effects vary with the period of gestation.

Maternal and cord blood levels of insulin-like growth factors--I and--II and insulin-like growth factor binding protein-1: correlation with birth weight and maternal anthropometric indices

OBJECTIVES

To study the correlation of maternal and cord blood insulin like growth factor (IGF)-I and -II and IGF binding protein (IGFBP)-1 levels with birth weight and maternal anthropometric indices.

DESIGN

Longitudinal prospective study.

SETTING

Academic Institutions and a Tertiary Care Maternity Hospital.

PARTICIPANTS

Women with uncomplicated singleton pregnancy (N = 35) and their newborns.

MEASUREMENTS

Maternal weight, height, symphysiofundal height and serum levels of IGF-I, IGF-II, IGFBP-1 were measured thrice during the antenatal period, within 24 h of delivery and at 6 weeks and 6 months postpartum. Newborn anthropometric indices were recorded at birth, and at 6 weeks and 6 months of age. Cord blood levels of IGF-1, IGF-II, IGFBP-1, paternal height and weight, and placental weight measured.

RESULTS

Maternal and cord blood IGF-I levels were lower than values reported for Caucasians. All newborns showed adequate growth at birth, and up to 6 months of age. Cord blood IGF-1 positively correlated with chest circumference (r = 0.4532, P = 0.0262), IGFBP-1, negatively with birth weight (r = -0.4024, P = 0.0461) and IGF-II had no effect. Cord blood IGF-I positively correlated with maternal levels at 28 +/- 2 (r = 0.4571, P = 0.0247) and 36 +/- 2 (r = 0.4291, P = 0.0364) weeks of amenorrhoea, whereas IGF-II and IGFBP-1 did not correlate with maternal values. Maternal IGF-I, IGF-II and IGFBP-1 did not correlate with newborn or maternal anthropometric indices. Placental weight correlated significantly with birth weight (r = 0.5299, P = 0.0348) and head circumference (r = 0.5031, P = 0.0470).

CONCLUSIONS

Cord blood IGFBP-1 and placental weight appear to be determinants of birth weight variation even among appropriately grown for gestational age newborns.