1 Department of Obstetrics and Gynaecology and 2 Section of Endocrinology, Department of Medicine, St Olavs Hospital, University Hospital of Trondheim, 3 Institute of Community Medicine and General Practice and 4 Institute of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
5 To whom correspondence should be addressed at: Department of Obstetrics and Gynaecology, St Olavs Hospital, University Hospital of Trondheim, Olav Kyrres g. 17, N-7006 Trondheim, Norway. Email: eszter.vanky{at}medisin.ntnu.no
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Abstract |
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Key words: androgens/metformin/PCOS/pregnancy outcome
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Introduction |
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One major concern in PCOS is reduced fertility. The rate of first trimester pregnancy loss is also considerably increased (Homburg et al., 1988; Sagle et al., 1988
; Regan et al., 1990
; Balen et al., 1993
; Tulppala et al., 1993
; Clifford et al., 1994
; Okon et al., 1998
; Jakubowicz et al., 2002
). The incidence of pregnancy complications in the second and third trimester among PCOS patients has been only sparsely studied. Gestational diabetes mellitus (GDM), pre-eclampsia (PE), and premature delivery has been associated with PCOS (Diamant et al., 1982
; Gjonnaess, 1989
; de Vries et al., 1998
; Radon et al., 1999
; Mikola et al., 2001
; Bjercke et al., 2002
). At least in Norway, pregnancies in PCOS women are not considered to be high-risk pregnancies.
The use of the anti-diabetic drug metformin in the treatment of non-pregnant PCOS women is quite well established (Wortsman et al., 1991; Velazquez et al., 1994
, 1997
; Nestler and Jakubowicz, 1997
; Morin-Papunen et al., 1998
; Moghetti et al., 2000
; Pasquali et al., 2000
; Fleming et al., 2002
). However, the effect of metformin in pregnant women has not been studied in detail. Studies from South Africa found no adverse effects of metformin in pregnant women with GDM (Coetzee and Jackson, 1979
, 1984
), whereas a non-randomized Danish study reported that metformin treatment was associated with an increased prevalence of PE and high perinatal mortality in diabetic women when compared with sulphonylurea treatment (Hellmuth et al., 2000
). This study, however, lasted for decades and the women in the metformin group were significantly more obese than in the control group. An observational study without control group reported a decreased first trimester pregnancy loss among women treated with metformin in early pregnancy (Glueck et al., 2002a
), and they also found that metformin therapy throughout pregnancy reduced the incidence of GDM from 40 to 4% in PCOS women (Glueck et al., 2002b
).
Pregnant PCOS women have higher androgen levels than their age- and weight-matched controls (Sir-Petermann et al., 2002). Elevated androgen levels later in life have been associated with prior pre-eclampsia (Laivuori et al., 1998
). In a case report, metformin markedly reduced androgen levels in a hyperandrogenic, pregnant woman who was treated with metformin to prevent masculinization of a female fetus (Sarlis et al., 1999
). In monkeys, premature labour and delivery can be induced in the early third trimester with i.v. administration of androstenedione (Mecenas et al., 1996
). We hypothesized that metformin would reduce androgen levels in pregnant PCOS women and that reduced androgen levels might, directly or indirectly, influence pregnancy complications and/or pregnancy outcome.
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Materials and methods |
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The inclusion criteria for the study were: (i) diagnosis of PCOS before the actual pregnancy, (ii) age 1840 years, (iii) gestational age between 5 and 12 weeks, and a singleton viable fetus judged by ultrasonography.
The exclusion criteria were known liver disease, creatinine >130 mmol/l, known alcohol abuse, previously known diabetes mellitus, fasting plasma glucose >5.6 mmol/l, treatment with oral glucocorticoids or use of drugs known to interfere with metformin. One of the authors (E.V.) enrolled all the participants.
Eighteen women were randomized to metformin medication and 22 to placebo (Figure 1). Two women, one in each group, withdrew within 2 weeks after inclusion. One cited a long distance to the hospital and the other had motivation failure. The remaining 38 women completed the study. The randomization and encapsulation of metformin and placebo to identical capsules were performed at the Trondheim University Hospital Pharmacy.
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At conception, 11 women in the placebo group and eight in the metformin group used metformin. Seven of the women who used metformin at conception (five in the placebo group and two in the metformin group) continued to use it until a few days before inclusion. All women had a wash out period of 2 days before inclusion. Inclusion, randomization, oral glucose tolerance test (OGTT) and drawing of blood samples occurred on the same day. Study medication was started the next morning.
At randomization (pregnancy week 512) and later at gestational week 19, 32 and 36, venous blood samples were drawn from an antecubital vein, between 08:00 and 11:00 after an overnight fast. Blood samples were centrifuged at room temperature within 30 min and stored at 70°C until analysis (128 months). A 75 g OGTT was performed according to the World Health Organization (1998) recommendations at inclusion and at gestational weeks 19 and 32 WHO consultation group (1998), Expert committe (1998).
Blood pressure was measured while the patient was in the sitting position after 15 min of rest. The blood pressure was measured three times,
2 min apart. The mean of the second and third measurement was calculated. All patients were followed up and treated during pregnancy according to standard antenatal care. A blinded evaluation of all maternal and infant diagnoses was performed by one of the authors (R.H.).
Study protocol
All participants received individual, verbal and written, diet and lifestyle counselling at inclusion. Thereafter treatment with metformin 425 mg (metformin hydrochloride, Metformin®; Weifa AS, Norway) or identical placebo capsules was initiated. All participants used two capsules once daily during the first week and two capsules twice daily for the rest of the study period. In addition, they all received a 1 mg tablet of folate daily, and one daily multivitamin tablet containing: vitamin A 800 mg, vitamin B1 1.4 mg, vitamin B2 1.6 mg, vitamin B6 2 mg, vitamin B12 1 mg, folic acid 200 mg, niacin 18 mg, pantotenic acid 6 mg, vitamin C 60 mg, vitamin D 5 mg, vitamin E 10 mg, Fe2 + 14 mg, Zn+ 15 mg, Cu2 + 2 mg, iodine 150 mg, Mn2 + 2.5 mg, Cr+ 50 mg, and Se+ 50 mg (Vitaplex®; Alpharma AS, Norway).
Primary outcome measures were dehydroepiandrosterone sulphate (DHEAS), androstenedione, testosterone, SHBG and free testosterone index (FTI). Secondary outcome measures were pregnancy outcome and pregnancy complications.
A written informed consent was obtained from each patient before inclusion and the declaration of Helsinki was followed throughout the study. The Committee for Medical Research Ethics of Health Region IV, Norway, and The Norwegian Medicines Agency approved the study.
Assays
Serum glucose was analysed, on the blood sampling day, by a glucose dehydrogenase method after protein precipitation with perchloric acid using the Merck Granutest 250 reagent kit (E.Merck, Germany). The rest of the blood tests were performed in serum. Testosterone and androstenedione were measured by a double antibody technique on an Elecsys 2010 analyser (Roche Diagnostics GmbH, Germany) using reagents and calibrators supplied by the manufacturer. SHBG and DHEAS were measured using a competitive immunoassay on an Immulite 2000 analyser using the reagents and calibrators supplied by the manufacturer (Diagnostic Products Corp., USA). FTI was calculated as total testosterone divided by SHBG and multiplied by a factor of 100. The lower and upper reference values for non-pregnant women were 0.9 and 11.7 mmol/l for DHEAS, 0.7 and 11.0 nmol/l for androstenedione, 0.1 and 2.9 nmol/l for testosterone, and 18 and 114 nmol/l for SHBG. All analyses except for glucose were performed in a single kit on the same day. Gestational diabetes was defined according to World Health Organization (1998) criteria, i.e. 2 h plasma glucose values
7.8 mmol/l during an OGTT with 75 g glucose WHO consultation group (1998), Expert committe (1998). Uncomplicated GDM treated with dietary advice only was not ranked among the complications in this study. pH was measured in umbilical artery blood, immediately after delivery on a Rapidlab 248pH/Blood Gas Analyzer, using reagents and calibrators supplied by the manufacturer (Bayer Corp., USA).
Pre-eclampsia was defined as a blood pressure 140/90 mmHg with concomitant albuminuria
0.3 g/24 h measured on two separate occasions after gestational week 20. Premature delivery was defined as delivery before gestational week 37+0 according to an estimated date of delivery, based on mid-trimester ultrasound scan.
Statistical analysis
All statistical procedures were performed using the SPSS version 11.0 for Windows (SPSS Inc., USA). For sample size calculations, we acheived 1617 patients in each group at 80% power to detect a 1.0 nmol/l difference in change of testosterone level between groups when assuming SD of 1.0 nmol/l. To evaluate treatment effects, the changes in hormone levels from inclusion to week 19, 32 and 36 were calculated for each woman. The differences in change between the study groups were compared with two-tailed t-tests for independent samples for normally distributed variables. Non-parametric tests for independent samples were applied for variables with skewed distributions. Fisher's exact test was used for evaluation of discrete data. Values are reported as means (SD). Two-tailed P<0.05 was considered significant. No adjustments for multiple comparisons were performed. Data on pregnancy complications and pregnancy outcome were analysed according to the intention to treat principle.
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Results |
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Twenty-two of the 40 women in the study had been pregnant previously, with a total of 38 pregnancies. These pregnancies resulted in 17 (45%) spontaneous abortions, three (8%) legal abortions, and 18 (47%) live-born infants with a mean birthweight of 3560 g and a mean gestational age of 38 weeks.
In the actual pregnancy, seven women conceived spontaneously: three in the placebo and four in the metformin group. Nineteen patients used metformin for ovulation induction when conceiving, 11 in the placebo and eight in the metformin group. Four patients received clomiphene citrate to become pregnant, two in each group, and 10 patients became pregnant after IVF or ICSI, six in the placebo and four in the metformin group.
Androgen levels
At inclusion, androgen levels and SHBG were equal in the two study groups. Further, the change from inclusion to gestational week 19, 32 and 36 did not differ, with respect to DHEAS, androstenedione, testosterone, SHBG or FTI, between the groups (Table II).
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In the post-partum period, serious complications occurred in three women in the placebo group. One woman (patient 8) who was delivered prematurely by emergency Caesarean section (CS) on fetal indication developed endometritis and group A streptococcus sepsis. Another woman (patient 9) developed unexplained acute respiratory distress syndrome (ARDS), after emergency CS on fetal indication. Assisted ventilation was required for 4 days. A third woman (patient 10) with uncomplicated vaginal delivery returned 12 days after discharge from the maternity unit with low abdominal pain and respiratory distress. A large pelvic vein thrombosis and massive lung embolism was diagnosed.
When comparing the number of patients with pregnancy-related complications in the placebo group (10/22, 45%) and in the metformin group (3/18, 17%) (Table III), a tendency towards reduction of complications (P=0.09) was observed in the metformin group. Severe pregnancy-related complications occurred only in the placebo group (7/22; 32% versus 0/18, 0%, P=0.01).
Seven out of 40 women (18%) were delivered by emergency CS, four (18%) in the placebo and three (17%) in the metformin group. The overall CS rate at the University Hospital of Trondheim is currently 15% and the emergency CS rate is
9% of all deliveries.
OGTT and gestational diabetes mellitus
None of the women had known diabetes mellitus before conceiving and all had normal fasting plasma glucose at inclusion (range 4.05.3 mmol/l). None of the women had been diagnosed with GDM during former pregnancy. At inclusion, prior to any study intervention, eight out of 40 patients (20%) had 2 h plasma glucose levels 7.8 mmol/l, at OGTT. After the initial OGTT, two of these patients were randomized to the metformin group and six patients to the placebo group. Thus, according to the WHO criteria, these eight patients had GDM already at the time of inclusion. Another three patients had elevated 2 h plasma glucose values at gestational week 19, two in the metformin group and one in the placebo group. At gestational week 32, another six patients showed pathological 2 h plasma glucose values, four in the metformin and two in the placebo group. In all, 17 (42%) pregnant women with PCOS met the criteria for GDM through pregnancy, nine in the placebo group and eight in the metformin group. All of these patients were treated with additional diet and lifestyle advice and self-monitoring of blood glucose. Two women in the placebo group and none in the metformin group required additional treatment with insulin. Insulin therapy was considered necessary if self-monitored fasting blood glucose was >5.5 mmol/l and/or the 1 h postprandial blood glucose was >8.0 mmol/l on more than two occasions. The aims of the insulin therapy were to keep the fasting blood glucose values
5.5 mmol/l and the 1 h glucose values
8.0 mmol/l (Metzger and Coustan, 1998
; Jovanovic and Pettitt, 2001
).
Metformin tolerability
None of the 38 women completing the study stopped the study medication. Six patients, three in each group, reported persistent nausea and gastrointestinal discomfort. They were instructed to reduce medication intake to one capsule twice daily.
Infants
The difference in gestational age, gestational length, head circumference and birthweight between the groups did not reach statistical significance. Placental weight, Apgar scores at 5 and 10 min, and pH of the umbilical vein did not differ between the groups (Table IV). No major anatomical malformations were observed. Minor anatomical abnormalities were seen in seven infants. In the placebo group there were two infants with pes equino-varus (patients 1 and 12), one with bilateral cryptorchidism (patient 10) and one with a large haemangioma on the hip (patient 11). In the metformin group there were two infants with a periauricular adnex (patients 24 and 26) and one with unilateral cryptorchidism (patient 27).
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Discussion |
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Severe pregnancy complications were significantly less frequent in the metformin group than in the placebo group. Although pregnancy complications and outcomes were secondary outcome measures, this must be regarded as the most important observation of our study. A remarkable finding is the occurrence of five premature deliveries (23%) in the placebo group. We can offer no explanation to this observation.
Pre-study metformin treatment could theoretically have influenced our results. However, the stratification was specifically aimed to control for pre-randomization use of metformin. It is hence unlikely that pre-randomization use of metformin influenced our data with respect to androgen levels or other parameters in the two treatment groups. In the present study, we found that 20% of the women fulfilled the criteria for GDM already at the time of inclusion, around the eighth week of pregnancy. The present study was neither designed nor powered to investigate the effects of metformin on the incidence of GDM. However, the total GDM incidence of 42% throughout pregnancy supports earlier observations of a high prevalence of GDM in PCOS patients (Radon et al., 1999; Mikola et al., 2001
). Our finding in a randomized controlled design does not support a 90% reduction of GDM by metformin in PCOS women reported by Glueck et al. (2002b)
. The discrepancy, in the findings and conclusions, of the present study and the studies by Glueck et al. with regard to the metformin effect on maternal androgen levels and GDM are noteworthy. We believe that this underlines the importance of performing prospective, randomized, placebo-controlled studies in conditions where diet and lifestyle intervention is known or suspected to affect the outcome or where the natural course of the disease is sparsely investigated. However, the results of the present study should be interpreted with caution due to the limited number of participants.
If our results are representative for pregnancies in PCOS women, one might speculate why the high frequency of complications is not a well-known phenomenon among clinicians. Possibly, when women present in mid and late pregnancy the physicians pay less attention to former irregular menstruations, centralized adiposity, and hirsutism. Another possible explanation for the frequent complications might be the high percentage of assisted fertilization, ovulation stimulation and metformin use at conception, indicating that our patients might represent a group of PCOS women with more extreme metabolic and endocrine changes than the average women with PCOS.
Although mean BMI was not significantly different between the placebo and metformin groups, it was distributed unevenly between groups. Eleven of the women in the placebo group versus four in the metformin group had a BMI <30 kg/m2. High BMI is associated with increased incidence of pregnancy complications. Since theoretically it would give more complications in the metformin group, not in the control group, this should only lead to conservative estimates of effect. As we had five premature deliveries in the placebo group, weight gain differences between the groups through pregnancy is difficult to interpret.
Nausea and mild gastrointestinal discomfort are common complaints in pregnancy. The most frequent side-effect of metformin is also gastrointestinal discomfort Physician Desk Reference (1999). Hence, we anticipated that metformin might enforce nausea and vomiting in pregnant PCOS women. However, metformin 850 mg twice daily was well tolerated and dose reduction was seldom necessary. Lactoacidosis is a rare but serious complication of metformin treatment. Whether metformin passes from the mother to the fetus in humans is not known. If it does, it is reassuring that we were unable to detect an effect on umbilical artery pH at birth. This indicates that maternal metformin treatment does not lead to lactic acidosis in the fetus.
We conclude that metformin treatment appears to be safe in pregnant PCOS women. It does not affect maternal androgen levels and is well tolerated. Severe pregnancy complications seem to be prevented by metformin in PCOS patients. If our data are confirmed by future studies, metformin might become a safe and inexpensive treatment for prevention of mid and late pregnancy complications in women with PCOS. Hence, sufficiently powered, randomized, clinical trials should be initiated to study the effect of metformin treatment on the different pregnancy complications associated with PCOS.
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Acknowledgements |
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References |
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Submitted on February 5, 2004; accepted on May 6, 2004.