In utero gender dimorphism of adiponectin reflects insulin sensitivity and adiposity of the fetus

Circulating adiponectin reflects the degree of energy homeostasis and insulin sensitivity of adult individuals. Low abundance of the high molecular weight (HMW) multimers, the most active forms mediating the insulin-sensitizing effects of adiponectin, is indicative of impaired metabolic status. The increase in fetal adiponectin HMW compared with adults is a distinctive features of human neonates. To further understand the functional properties of adiponectin during fetal life, we have evaluated the associations of adiponectin with insulin sensitivity, body composition, and gender. Umbilical cord adiponectin, adiponectin complexes, and metabolic parameters were measured at term by elective cesarean delivery. The associations between adiponectin, measures of body composition, and insulin sensitivity were evaluated in relation to fetal gender in 121 singleton neonates. Higher total adiponectin concentrations in female compared with male fetuses (34.3+/-9.5 vs. 24.9+/-8.6, P<0.001) were associated with a 3.2-fold greater abundance in circulating HMW complexes (0.20+/-0.03 vs. 0.08+/-0.03, P<0.001, n=9). Adiponectin was positively correlated with neonatal fat mass (r=0.27, P<0.04) and percent body fat in female fetuses (r=0.28, P<0.03) and with lean mass in males (r=0.28, P<0.03). There was no significant correlation between cord adiponectin and fasting insulin concentrations or fetal insulin sensitivity as estimated by homeostasis model assessment of insulin resistance (HOMA-IR). The gender dimorphism for plasma adiponectin concentration and complex distribution first appears in utero. In sharp contrast to the inverse correlation found in adults, the positive relationship between adiponectin and body fat is a specific feature of the fetus.

High molecular mass multimer complexes and vascular expression contribute to high adiponectin in the fetus

CONTEXT

High plasma adiponectin concentrations in human fetuses and neonates are unique features of early developmental stages. Yet, the origins of the high adiponectin concentrations in the perinatal period remain elusive.

OBJECTIVE

This study was undertaken to identify the sources and functional properties of adiponectin in utero.

DESIGN AND METHODS

Tissue specimens were obtained at autopsy from 21- to 39-wk-old stillborn human fetuses. Adipose tissue and placenta were obtained at term elective cesarean section. Adiponectin complexes and expression were measured by immunodetection and real-time PCR.

RESULTS

Adiponectin mRNA transcripts were detected in fetal sc and omental adipose depots at lower concentrations than in maternal adipose tissue. Immunoreactive adiponectin was also observed in vascular endothelial cells of fetal organs, including skeletal muscle, kidney, and brain. The absence of adiponectin in all placental cell types and lack of correlation between maternal and umbilical adiponectin indicate that umbilical adiponectin reflects its exclusive production by fetal tissues. The most prominent forms of adiponectin in fetal plasma were high and low molecular mass (HMW and LMW) multimers of 340 and 160 kDa, respectively. The proportion of the HMW complexes was 5-fold (P < 0.001) higher in umbilical plasma than in adult. The high HMW and total adiponectin levels were associated with lower insulin concentration and lower homeostasis model of assessment of insulin resistance indices in umbilical plasma, reflecting higher insulin sensitivity of the fetus compared with adult.

CONCLUSIONS

The abundance of HMW adiponectin and its vascular expression are characteristics of human fetal adiponectin. Combined with high insulin sensitivity, fetal adiponectin may be a critical determinant of in utero growth.

Impact of weight loss between pregnancies on recurrent preterm birth

OBJECTIVE

Low maternal pre-pregnancy body-mass index (BMI) has been associated with preterm birth (PTB). Women delivering preterm are at increased for recurrent PTB. Our goal was to determine whether change in BMI between pregnancies alters the risk of PTB.

STUDY DESIGN

From our electronic perinatal database, we identified women who delivered consecutive pregnancies at our institution. Women were grouped by prepregnancy BMI category (underweight: <18.5, normal: 18.5-24.9, overweight: 25-29.9, obese: >30 kg/m2). They were then grouped based on change in actual BMI ("increase": >5 kg/m2, "stable": within 5 kg/m2, "decrease": >5 kg/m2) and change in BMI category between pregnancies. The risk of PTB was correlated to change in BMI. P < .05 was considered significant.

RESULTS

One thousand two hundred forty-one women met inclusion criteria. Women with a PTB in their first pregnancy had more PTB in their second than those with a term birth in their first pregnancy (33.6% vs 8.0%, P < .001). Women whose BMI decreased more than 5 kg/m2 had more frequent PTB in the second pregnancy than those who did not (21.1% vs 9.3%, P = .01). For those with a term birth in the first pregnancy, PTB in the second did not increase with declining BMI. However, for women with a PTB in the first pregnancy, PTB was more frequent in the second if their BMI decreased a BMI category (53.8% vs 27.6%, P = .05) or if BMI decreased more than 5 kg/m2 (80.0% vs 28.2%, P = .01).

CONCLUSION

Women whose BMI declines between pregnancies are at increased risk for PTB, particularly if they delivered a prior preterm gestation.