Increased risk of preterm delivery and pre-eclampsia in women with polycystic ovary syndrome and hyperandrogenaemia

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1 DOI: / Fertility and assisted reproduction Increased risk of preterm delivery and pre-eclampsia in women with polycystic ovary syndrome and hyperandrogenaemia KV Naver, a J Grinsted, b SO Larsen, c PL Hedley, c,d FS Jørgensen, a M Christiansen, c L Nilas a a Department of Obstetrics and Gynaecology, Hvidovre University Hospital, University of Copenhagen, Hvidovre, Denmark b The Fertility Clinic Trianglen, Hellerup, Denmark c Department of Clinical Biochemistry, Immunology, and Genetics, Statens Serum Institut, Copenhagen, Denmark d Department of Biomedicine, University of Stellenbosch, Cape Town, South Africa Correspondence: Dr KV Naver, Department of Obstetrics and Gynaecology, Hvidovre University Hospital, University of Copenhagen, Kettegård alle 30, DK 2650, Hvidovre, Denmark. kvnaver@gmail.com Accepted 18 October Published Online 13 January Objective To study the risk of adverse pregnancy outcomes in women with polycystic ovary syndrome (PCOS), and to examine the role of hyperandrogenaemia. Design Cohort study. Setting Singleton pregnancies in women with PCOS identified at a private fertility clinic during and a background population including all singleton deliveries at Hvidovre Hospital, Denmark, in Population A cohort of 459 women with PCOS and a background population of 5409 women. Methods Obstetric outcomes were extracted from national Danish registries and odds ratios (ORs) were calculated by multiple logistic regression analysis, adjusting for age, parity, and body mass index. Main outcome measures Risk of pre-eclampsia, preterm delivery, and small for gestational age offspring in the entire PCOS population and in a subsample with hyperandrogenaemia. Results Women with PCOS had an increased risk of preterm delivery <37 weeks of gestation (OR 2.28; 95% confidence interval, 95% CI, ; P < ). The elevated risk was confined to hyperandrogenic women with PCOS: preterm delivery before 37 weeks of gestation (OR 2.78; 95% CI ; P < ), and was not seen in normoandrogenic women with PCOS (OR 1.35; 95% CI ; P = 0.52). The overall risk of pre-eclampsia was not elevated (OR 1.69; 95% CI ; P = 0.05) compared with the background population, but was significantly increased in the hyperandrogenic subsample (OR 2.41; 95% CI ; P < 0.001). The risk of small for gestational age offspring was similar in all groups. Conclusion Women with PCOS had an increased risk of preterm delivery compared with the background population. The increased risk was confined to hyperandrogenic women with PCOS who had a two-fold increased risk of preterm delivery and pre-eclampsia. Keywords Hyperandrogenaemia, polycystic ovary syndrome, pre-eclampsia, preterm delivery. Please cite this paper as: Naver KV, Grinsted J, Larsen SO, Hedley PL, Jørgensen FS, Christiansen M, Nilas L. Increased risk of preterm delivery and pre-eclampsia in women with polycystic ovary syndrome and hyperandrogenaemia. BJOG 2014;121: Introduction Polycystic ovary syndrome (PCOS) is the most common endocrinopathy among fertile women, affecting 5 10% in different ethnic populations. PCOS is a heterogeneous disorder and is associated with insulin resistance, dyslipidaemia, and increased long-term risk of type II diabetes. The PCOS diagnosis according to the 2003 Rotterdam criteria includes any two or all three of the following features: menstrual irregularities; polycystic ovaries; and hyperandrogenism. 1 As a consequence of anovulation, fertility treatment is often necessary to achieve a pregnancy. Recent studies indicate an increased risk of pregnancy complications such as pre-eclampsia, gestational diabetes, preterm delivery, and hypertension in PCOS pregnancies. 2 The pathophysiological explanation is debated, as several characteristics of the PCOS population, including obesity and the use of assisted reproductive techniques, are potential confounding factors. A Swedish register-based study found an increased risk of several adverse pregnancy outcomes (gestational diabetes, pre-eclampsia, preterm delivery, large for gestational age, and small for gestational age infants) in 575

2 Naver et al women with PCOS, compared with the background population after adjusting for assisted reproductive techniques, body mass index (BMI), maternal age and educational attainment. 3 Populations of women with PCOS are heterogeneous, and it seems likely that not all phenotypes have identical risks of adverse pregnancy outcome. One study reports a wide variation in the risks of adverse pregnancy outcome between the Rotterdam PCOS phenotypes, with the most frequent occurrence in women fulfilling all three Rotterdam PCOS criteria. 4 The aim of this study was to compare the risk of pre-eclampsia, preterm delivery, and small for gestational age offspring in a cohort of women with PCOS with that of a background population, and to examine the role of hyperandrogenaemia as a risk factor. Methods The PCOS population We identified a cohort of women with PCOS treated at the private fertility clinic Trianglen in Copenhagen, Denmark. In addition to a PCOS diagnosis according to the 2003 European Society of Human Reproduction and Embryology (ESHRE)/American Society for Reproductive Medicine (ASRM) Rotterdam criteria, 1 a singleton delivery during the time period was also used as an inclusion criterion. Exclusion criteria were a diagnosis of type I or type II diabetes prior to pregnancy. According to the Rotterdam criteria, PCOS is diagnosed if two or three of the following criteria are fulfilled: (1) polycystic ovaries; (2) clinical or biochemical hyperandrogenism; (3) oligo- or amenorrhoea. Information concerning ovarian morphology and menstrual pattern were retrieved from patient files. Menstrual pattern was categorised as regular cycles, oligomenorrhoea (>35 days and <6 months between bleeding) or amenorrhoea (>6 months without bleeding). If only oligomenorrhoea or amenorrhoea was noted by the doted, this was accepted. The ovaries were classified as polycystic or normal, as described by the gynaecologist. The method of conception was registered as natural conception, intrauterine insemination homologue, or donor [including: ovulation induction (IUI); in vitro fertilization (IVF); frozen embryo replacement (FER); or intracytoplasmic sperm injection (ICSI)]. A transvaginal ultrasound examination was performed in the first trimester confirming the gestational age and expected date of delivery. The first singleton pregnancy with available information from patient files on mode of fertilisation was chosen as the index pregnancy. In the case of a multiple pregnancy we selected the singleton pregnancy prior to the multiple pregnancy (first choice) or the singleton pregnancy following the multiple pregnancies, if available. Initially, 482 women diagnosed with PCOS, and who had a live singleton pregnancy at first trimester, were identified from the fertility clinic. We excluded 23 cases for type I or type II diabetes prior to pregnancy (n = 3), pregnancy loss before 22 weeks of gestation (n = 19), and lack of information on obstetric or neonatal outcomes (n = 1). The final study population consisted of 459 women. BMI was available in 61% (n = 281) and an androgen evaluation was available in 64% (n = 295) of the PCOS population. Information on ovarian morphology and menstrual pattern was available in all women with PCOS. In the PCOS group 24.5% (n = 117) were treated with a biguanide before or during the first trimester in their index pregnancy. The methods of conception were: 238 IUI (51.9%), 132 IVF/ ICSI/FER (28.8%), 83 natural conceptions (18.1%), and six unknown (1.3%); 61 (13%) women had amenorrhoea, 380 (83%) had oligomenorrhoea, and 18 (4%) had regular cycles. Background population The background population was represented by a birth cohort including all singleton deliveries from the year 2005 at the Copenhagen University Hospital Hvidovre, the largest obstetrical department in Denmark. The public hospital is located in an urban area 13 km from the fertility clinic, and treats women of both high and low education and income status. The year 2005 was chosen as first-trimester screening was introduced in Denmark in 2004 with a high rate of attendance. As a consequence, gestational age and estimated date of delivery was estimated from crown rump length (CRL) measurements at a first-trimester transvaginal or transabdominal ultrasound. Information on baseline characteristics and obstetric outcome were identical, with reference to the tenth edition of the International Classification of Diseases (ICD10) codes, to the data retrieved regarding the PCOS population. Eight women were excluded from the background population as they were patients at the fertility clinic Trianglen and already part of the PCOS population. All data available were prospectively collected. Information on PCOS diagnosis, fertility treatment, or androgen measurements were not available in the total background population. The background population consisted of 5409 women with a singleton delivery after 22 weeks of gestation. BMI was available for 96% (n = 5207). Measurements of androgens During the study period all measurements of androgens were performed at the Statens Serum Institut (SSI), Copenhagen, Denmark. Using the unique Danish personal identification number of each woman, all androgen measurements in the PCOS population taken at the time of diagnosis or treatment were retrieved from the files at SSI. These measurements included total testosterone and sex 576

3 Preterm delivery and pre-eclampsia in women with PCOS hormone-binding globulin (SHBG), and were used in the determination of free testosterone. Testosterone was measured by radioimmunoassay (RIA) after ether extraction followed by celite chromatography. The intra- and inter-assay variations were 8.2 and 13.8%, respectively. The detection limit was 0.05 nmol/l. SHBG was analysed by a double-monoclonal immunofluorometric assay (AutoDelfia; Wallac, Oy, Turku, Finland). Intra- and inter-assay variations were 5.2 and 7.5%, respectively. Free testosterone was estimated as described previously, 5 based on the measured concentrations of SHBG, total testosterone and dihydrotestosterone, and the use of the law of mass action, using the binding constant of testosterone and dihydrotestosterone to SHBG, and including a calculation of testosterone binding to albumin. 6 The normal range for plasma total testosterone levels was nmol/l, and the range for plasma free testosterone levels in premenopausal women was nmol/l. SHBG values exceeding the upper normal level of 170 nmol/l were excluded from statistical analysis. A woman with PCOS was considered hyperandrogenaemic if total testosterone was above 1.8 nmol/l, and/or free testosterone was above nmol/l. In cases with several measurements of androgens, we chose the androgens measured at the date closest to the index pregnancy. Obstetric outcome Information on all births was retrieved from the Danish Medical Birth Register and the Danish National Patient Register. 7,8 The Danish Medical Birth Register includes information on all live-born children and stillbirths after 22 weeks of gestation in Denmark using ICD10 codes. Information on maternal age, parity, maternal BMI (from 2004 and onwards), birthweight, gender, gestational age, birth length, pre-eclampsia, hypertension during pregnancy, caesarean section, induction of labour, and neonatal death was extracted from the Danish Medical Birth Register, and the diagnosis of gestational diabetes was extracted from the Danish National Patient Register. Pre-eclampsia was diagnosed if proteinuria (>3 g during 24 hours or +1 ona sterile dipstick) and a blood pressure above 140/90 mmhg were present. According to national guidelines gestational diabetes was defined as plasma glucose levels > 10.0 mmol/ l or more after a 2 hour oral glucose tolerance test (with 75 g of glucose). Data from the patient files and the Danish Medical Birth Register were linked using the unique personal identification number. The diagnosis of PCOS is not registered in the Danish Medical Birth Register, and is rarely available in obstetrical patient files. Our primary end points were pre-eclampsia, preterm delivery prior to 37 weeks of gestation, and small for gestational age offspring (z score < 78%). 9 Statistics Offspring size at birth was expressed as a z score: the deviation of the observed fetal weight from the estimated birthweight adjusted for sex and gestational age, and expressed as a percentage. 9 An offspring size at birth of <78% corresponds to a small for gestational age offspring (SGA) and an offspring size of >122% corresponds to a large for gestational age offspring (LGA). Continuous data were summarised as means SDs or medians (interquartile ranges), and compared using a two-- sided Student s t test. Categorical variables were summarised as counts and compared using the chi-square test (Table 2). Skewed data were log transformed and tested for normality. Multiple logistic regression analysis was used to identify variables with a significant impact on the risk of adverse pregnancy outcome in the background population and PCOS population. P < 0.05 was considered to be statistically significant. We used SAS 9.2 (SAS Institute Inc., Cary, NC, USA) and S PLUS 2000 (MathSoft, Inc., Seattle, WA, USA) for the analyses. Results The women with PCOS were slightly older (31.6 versus 30.7 years, P < 0.001), were more likely to be nulliparous (72.4 versus 57.1%, P < 0.001), and had a lower mean BMI (22.9 versus 23.4, P = 0.008) compared with the background population. In the PCOS population 19.2% of the women (n = 54) had a BMI 25 kg/m 2, versus 24.9% (n = 1297) in the background population. Obstetric outcome Women with PCOS had a shorter gestation (P = 0.04) and an increased risk of preterm delivery before 37 weeks of gestation (P = ), but not of very early delivery (<34 weeks of gestation), and an increased risk of pre-eclampsia (P = 0.018; Table 1). There was no significant difference between the two groups with respect to offspring birthweight, gestational age, and gender-adjusted birthweight, caesarean section, induction of labour, SGA offspring, LGA offspring, or hypertension (Table 1). The frequency of induction of labour was also identical in the two subgroups with preterm delivery before 37 weeks of gestation in 12.6% of controls versus 12.2% in the PCOS population, and preterm caesarean section rates for medical reasons (emergency or planned before labour) were comparable (P = 0.63; chi-square test). As 117 women with PCOS were treated with a biguanide before or during pregnancy, the use of biguanide was included in a multiple logistic regression analysis also containing BMI, age, and parity. The use of a biguanide had no significant effect on the risk of either pre-eclampsia 577

4 Naver et al. Table 1. Pregnancy outcomes in the PCOS population and background population given as means SDs or percentages Outcome PCOS (n = 459) Background population (n = 5409) Birthweight (g) 3448 (595) 3505 (552) 0.05 Gestational age (14.5) (12.7) 0.003* (days) Birth size** 99.2 (13.0) 99.3 (12.4) 0.91 Caesarean section, 101 (22) 1151 (21) 0.76 n (%) Pre-eclampsia, n (%) 25 (5) 164 (3) 0.008* Hypertension, n (%) 5 (1) 90 (2) Gestational diabetes, 11 (2.4) 57 (1.1) 0.019* n (%) Preterm delivery 41 (9) 253 (5) * <37 weeks of gestation, n (%) Preterm delivery 5 (1.1) 71 (1.3) 0.85 <34 weeks of gestation, n (%) Stillbirths/neonatal 2 (0.4) 18 (0.3) 0.96 death, n (%) Induction of labour, 84 (18) 800 (15) n (%) Small for 18 (4) 192 (4) 0.78 gestational age (<78%), n (%) Large for gestational age (>122%), n (%) 19 (4) 195 (4) 0.59 *P < **Gestational age and gender-adjusted birthweight expressed in percentages. P (P = 0.73) or preterm delivery before 37 weeks of gestation (P = 0.79) in the PCOS population, and was not included in the following statistical analysis. Furthermore, the distribution of IUI (54 versus 52%), IVF/ICSI/FER (24 versus 29%), and spontaneous pregnancies (19 versus 17%) was similar (chi-square P = 0.63) in women with and without hyperandrogenaemia. In a multiple regression analysis (correcting for the effects of a PCOS diagnosis, BMI, parity, and maternal age), a high BMI and nulliparity were both associated with an increased risk of pre-eclampsia (OR 1.77, 95% CI ; OR 3.18, 95% CI ), whereas age >39 years and nulliparity had a significant impact on the risk of a preterm delivery before 37 weeks of gestation (OR 2.35, 95% CI ; OR 1.31, 95% CI ; Table 2). When these factors were adjusted for, having a PCOS diagnosis remained associated with an increased risk of preterm delivery <37 weeks of gestation (OR 2.28; 95% CI ; P < ), but was not related to the risk of pre-eclampsia (OR 1.69; 95% CI ; P = 0.05). The PCOS population with available androgen measurements was hereafter divided into women who were hyperandrogenaemic (n = 184) and women who were normoandrogenaemic (n = 111) using the androgen measurements closest to the index pregnancy (Table 3). In a multiple logistic regression analysis adjusting for BMI, age, and parity, the OR of preterm delivery before 37 weeks of gestation was increased in hyperandrogenic women with PCOS (OR 2.78; 95% CI ; P < ), but not in normoandrogenic women with PCOS (OR 1.35; 95% CI ; P = 0.516), compared with the background population. Likewise, the OR for pre-eclampsia was 2.41 (95% CI ; P = ) in hyperandrogenic women with PCOS, but was not increased in normoandrogenic women Table 2. Odds ratios (ORs) for pre-eclampsia and preterm delivery in women with PCOS (n = 459) compared with the background population (n = 5409) Outcome Variable PCOS and background population Odds ratio adjusted* 95% CI P Preterm delivery before 37 weeks of gestation BMI > 30 kg/m Nulliparity ** Age > 39 years ** PCOS diagnosis <0.0001** Pre-eclampsia BMI > 30 kg/m ** Nulliparity <0.0001** Age > 39 years PCOS diagnosis *Multiple logistic regression analysis adjusting for BMI, age, and parity. **P <

5 Preterm delivery and pre-eclampsia in women with PCOS Table 3. Pre-eclampsia and preterm delivery in women with PCOS with (n = 184) and without (n = 111) pre-pregnancy hyperandrogenaemia, compared with the background population (n = 5409) Outcome Variables PCOS with hyperandrogenaemia, compared with a background population PCOS without hyperandrogenaemia, compared with a background population OR adj* 95% CI P OR adj* 95% CI P Preterm delivery before 37 weeks of gestation BMI > 30 kg/m Nulliparity ** ** Age > 39 years ** ** PCOS diagnosis <0.0001** Pre-eclampsia BMI > 30 kg/m ** Nulliparity <0.0001** <0.0001** Age > 39 years PCOS diagnosis ** *Odds ratios adjusted for age, BMI, parity, and PCOS diagnosis. **P < with PCOS (OR 0.73; 95% CI ; P = 0.657; Table 3). Discussion Main findings Women with PCOS and hyperandrogenaemia had a more than two-fold increased risk of both preterm deliveries before 37 weeks of gestation and of pre-eclampsia, compared with the background population, whereas normoandrogenic women with PCOS were not at an increased risk. To the best of our knowledge this finding has not been published before. The results indicate that hyperandrogenaemia rather than the PCOS diagnosis is a marker of preterm delivery and pre-eclampsia. Furthermore, the frequency of labour induction, before 37 weeks of gestation, was similar between the background population and PCOS population (12.6 and 12.2%). This suggests that preterm delivery is associated with the PCOS diagnosis and not caused by pregnancy complications such as, for example, growth restriction. The women with the greatest risk of late preterm delivery were older (>39 years), nulliparous women with hyperandrogenic PCOS. Late-preterm birth is a growing problem worldwide, and concern about both the short- and long-term consequences is increasing. Late-preterm infants have, compared with term infants, an increased risk of not only neonatal morbidity and mortality, but also of adverse long-term outcomes, including neurodevelopmental problems during childhood and adulthood. 10,11 An awareness of an increased risk of late preterm delivery in hyperandrogenic patients with PCOS is therefore essential, and the underlying pathways are yet to be discovered. Recent studies describe an increased risk of very preterm birth before 32 or 34 weeks of gestation in women with PCOS, which we were not able to confirm. 3,12 A high prevalence of cervical insufficiency has been reported in a PCOS population in the USA, compared with controls, but the pathophysiological mechanism linking PCOS and cervical insufficiency remains unknown. 13 PCOS is a heterogeneous and inconsistent condition, and others have found that insulin resistance possibly plays a role in the pathogenesis of pre-eclampsia in a PCOS population. 14 Insulin resistance was not analysed in our PCOS population, but an association between androgen levels and the degree of insulin resistance has previously been demonstrated in non-pregnant women with PCOS. 15 Women with PCOS and with normal androgen levels had no increased risk of pre-eclampsia or preterm delivery. We furthermore found no difference with respect to hypertension, growth restriction, or macrosomia comparing pregnancies in women with PCOS against a background population. These findings are in contrast to other previous studies that found an increased risk of pregnancy complications in PCOS populations. 3,16,17 The use of a biguanide improves insulin sensitivity, and non-randomised studies indicate a reduced risk of gestational diabetes in women with PCOS treated with biguanide during pregnancy. 18 However, the only existing randomised placebo-controlled trial in women with PCOS found no significant effect of Metformin â (Weifa AS, Oslo, Norway) on the risk of adverse pregnancy outcomes, 19 whereas a reanalysis of the data indicated a reduced risk of very preterm delivery in the Metformin â group. 20 We found no association between the use of biguanide before and/or during the first trimester and the risk of preterm delivery or pre-eclampsia in the PCOS population after adjusting for age, BMI, and parity. 579

6 Naver et al. Strengths and limitations Polycystic ovaries were described in virtually all women diagnosed with PCOS, clinical hirsutism was described in some, and the clinical diagnosis of oligo- or amenorrhoea was accepted. Androgen measurements were retrieved in 295 of the 459 women with PCOS, and all androgen measurements were performed with the same assay at SSI. If more than one androgen measurement was available, the one obtained closest to the index pregnancy was chosen. Testosterone levels in an individual may show large variability, which is partly explained by the inter- and intra-assay variation, but testosterone also varies during night, day, and during the menstrual cycle. All calculations were therefore repeated using the highest androgen values that gave the same results (data not shown). Information on androgens and fertility treatment was not available in the background population. Although we excluded women with PCOS treated at the fertility clinic from the background population, others in this cohort might have been hyperandrogenic. Excluding all hyperandrogenic women from the background population could result in an even larger difference in pregnancy outcome between the two populations. The majority of the PCOS population received fertility treatment, mostly ovulation induction/iui and IVF, and it is well documented that pregnancies after fertility treatment are associated with an increased risk of short gestations and adverse pregnancy outcomes, even in singleton pregnancies. 21,22 As a result we chose not to have a fertility cohort without PCOS from the fertility clinic as a control group. These women would most likely have other underlying causes of infertility increasing their risk of adverse outcomes during pregnancy. We were able to adjust for age, BMI, and parity, but because of the study design we were not able to take all factors into account. Residual confounding is therefore possible. Interpretation Polycystic ovary syndrome (PCOS) is the leading cause of anovulatory infertility, and a large Swedish register-based cohort study showed an increased risk of adverse pregnancy outcome in women with PCOS after adjusting for maternal age, BMI, and assisted reproductive technology. 3 Maternal metabolic, inflammatory, or hormonal profiles leading to infertility could increase the risk of adverse pregnancy outcome. 23,24 An impact of assisted reproductive techniques on pregnancy outcome cannot be ruled out, however, as culture media has been hypothesised to affect fetal growth, for example. 25 In contrast to other studies on women with PCOS, our PCOS population had a relatively low frequency of overweight, which may partly be explained by a lower risk of obesity in Denmark compared with the US or UK. Women with a PCOS diagnosis and a delivery are expected to represent the leaner fraction of the PCOS population, as the pregnancy rate is negatively affected by obesity, and assisted reproductive technology is seldom used in women with a BMI exceeding 35 kg/m 2, and is discouraged in women with a BMI > 40 kg/m 2. We cannot rule out the possibility of socio-economic selection, as the private fertility clinic is located in a high-income area and requires payment for IVF/ICSI treatment. Even so, we found an increased risk of gestational diabetes in the PCOS population compared with controls. Both BMI and a pre-pregnancy androgen measurement were only available in a few of the women with PCOS and gestational diabetes. As a result we were not able to investigate the impact of these variables. Conclusion We demonstrate an increased risk of preterm delivery and pre-eclampsia in a large cohort of PCOS patients, compared with a background population. Adjusting for age, BMI, and parity we identified that only women with PCOS in association with hyperandrogenaemia were at increased risk. Future clinical prospective studies in PCOS pregnancies are needed to investigate the association found between hyperandrogenaemia and risk of preterm delivery and pre-eclampsia. Disclosure of interests All authors declare that they have received no support from any organisation for this work, no financial relationships with any organisations that might have an interest in this work in the previous 3 years, and no other relationships or activities that could appear to have influenced this work. Contribution to authorship KN and LNI designed and carried out the study in cooperation with FSJ, JG, SOL, PHY, and MIC, and KN drafted the article. All authors revised the article and accepted the final version. SOL and KN performed the statistical analysis. Details of ethics approval The study was approved by The Danish Data Protection Agency ( ) on 20 November 2011 and by the National Board of Health ( /1) on 13 February Funding None. Acknowledgement None. & 580

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