**7. Polycystic ovary syndrome and pregnancy**

Normal pregnancy is characterized by induction of insulin resistance associated with com‐ pensatory hyperinsulinemia in second and third trimesters [49]. This insulin resistance of normal pregnancy is a physiologically advantageous adaptation designed to restrict maternal glucose uptake and to ensure shunting of nutrients to the growing fetus. It is probably mediated by increases in hormonal levels of estradiol, progesterone, prolactin, cortisol, human chorionic gonadotropin, placental growth hormone (PGH), and human placental lactogen (HPL) [33]. HPL and PGH are the hormones mainly responsible for insulin resistance in pregnancy. HPL is responsible for adaptive increase in insulin secretion necessary for preg‐ nancy and for diversion of maternal carbohydrate metabolism to fat metabolism in the third trimester. PGH seems to be a paracrine growth factor probably regulating the metabolic and growth needs of the fetus partially [92]. There is approximately 200 to 250% increase in insulin secretion in lean women with normal glucose tolerance with advancing gestation [93]. However, there is comparatively less robust increase in insulin levels of obese women with normal glucose tolerance.

As we state before, hyperandrogenism and insulin resistance are the metabolic hallmark of PCOS women. In these patients, the baseline insulin resistance seems to be exacerbated with entry into pregnancy. There is an increased risk of pregnancy complications in PCOS women [94]. Nowadays a growing body of evidence points to a high prevalence of pregnancy complications in PCOS women. PCOS was strongly associated increased risk of early preg‐ nancy loss, gestational diabetes (GDM), pregnancy-induced hypertension, preeclampsia, preterm birth, small for gestational age, large for gestational age, caesarean section, operative vaginal delivery, neonatal meconium aspiration and having a low Apgar score (<7) at five minutes and admission to an NICU [95-98].

It should be noted that there were the close link between PCOS and obesity and the association of obesity with poor pregnancy outcome, so, it might be possible that possible confounding effect of BMI play a role in adverse effect of PCOS on pregnancies.
