Hum. Reprod. Advance Access originally published online on December 11, 2007
Human Reproduction 2008 23(2):324-328; doi:10.1093/humrep/dem371
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Obesity affects spontaneous pregnancy chances in subfertile, ovulatory women
1 Department of Public Health, Erasmus MC, University Medical Centre Rotterdam, The Netherlands 2 Center for Reproductive Medicine, Academic Medical Centre, Amsterdam, The Netherlands 3 Department of Clinical Epidemiology and Biostatistics, Academic Medical Centre, Amsterdam, The Netherlands 4 Department of Obstetrics and Gynaecology, Vrije Universiteit Medical Centre, Amsterdam, The Netherlands 5 Department of Obstetrics and Gynaecology, Scheperziekenhuis Emmen, Emmen, The Netherlands 6 Department of Obstetrics and Gynaecology, Medisch Spectrum Twente, Enschede, The Netherlands 7 Department of Obstetrics and Gynaecology, Máxima Medical Centre, Veldhoven, The Netherlands
8 Correspondence address. Academic Medical Centre, Centre for Reproductive Medicine, Room H4-213, PO Box 22660, 1105 AZ Amsterdam, The Netherlands. Tel: +31-20-5663857; Fax: +31-20-6963489; E-mail: j.w.vandersteeg{at}amc.uva.nl
BACKGROUND: Obesity is increasing rapidly among women all over the world. Obesity is a known risk factor for subfertility due to anovulation, but it is unknown whether obesity also affects spontaneous pregnancy chances in subfertile, ovulatory women.
METHODS: We evaluated whether obesity affected the chance of a spontaneous pregnancy in a prospectively assembled cohort of 3029 consecutive subfertile couples. Women had to be ovulatory and had to have at least one patent tube, whereas men had to have a normal semen analysis. Time to spontaneous ongoing pregnancy within 12 months was the primary endpoint.
RESULTS: The probability of a spontaneous pregnancy declined linearly with a body mass index (BMI) over 29 kg/m2. Corrected for possible related factors, women with a high BMI had a 4% lower pregnancy rate per kg/m2 increase [hazard ratio: 0.96 (95% CI 0.91–0.99)].
CONCLUSIONS: These results indicate that obesity is associated with lower pregnancy rates in subfertile ovulatory women.
Key words: obesity/subfertility/pregnancy chance/spontaneous conception
Submitted on February 8, 2007; resubmitted on September 18, 2007; accepted on September 26, 2007.