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Loy SL, Cheung YB, Soh SE, Ng S, Tint MT, Aris IM, Bernard JY, Chong YS, Godfrey KM, Shek LP, Tan KH, Lee YS, Tan HH, Chern BSM, Lek N, Yap F, Chan SY, Chi C, Chan JKY. Female adiposity and time-to-pregnancy: a multiethnic prospective cohort. Hum Reprod 2019; 33:2141-2149. [PMID: 30285230 DOI: 10.1093/humrep/dey300] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 09/15/2018] [Indexed: 12/26/2022] Open
Abstract
STUDY QUESTION Are higher overall and central adiposity associated with reduced fecundability, measured by time-to-pregnancy (TTP), in Asian women? SUMMARY ANSWER Higher overall adiposity, but not central adiposity, was associated with longer TTP in Asian women. WHAT IS KNOWN ALREADY High body mass index (BMI) has been associated with a longer TTP, although the associations of body composition and distribution with TTP are less clear. There are no previous studies of TTP in Asian women, who have a relatively higher percentage of body fat and abdominal fat at relatively lower BMI. STUDY DESIGN, SIZE, DURATION Prospective preconception cohort using data from 477 Asian (Chinese, Malay and Indian) women who were planning to conceive and enrolled in the Singapore PREconception Study of long-Term maternal and child Outcomes (S-PRESTO) study, 2015-2017. PARTICIPANTS/MATERIALS, SETTING, METHODS Women's mean age was 30.7 years. Overall adiposity was assessed by BMI, sum of 4-site skinfold thicknesses (SFT) and total body fat percentage (TBF%, measured using air displacement plethysmography); central adiposity was assessed by waist circumference (WC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) and A body Shape Index (ABSI). Pregnancy occurring within one year from recruitment was ascertained by ultrasonography. Those who did not conceive within one year of recruitment, were lost to follow-up, or initiated fertility treatment were censored. TTP was measured in cycles. Discrete-time proportional hazards models were used to estimate the fecundability ratio (FR) and 95% confidence interval (CI) for each anthropometric measure in association with fecundability, adjusting for confounders. MAIN RESULTS AND THE ROLE OF CHANCE Compared to women with a normal BMI of 18.5-22.9 kg/m2, women with higher BMI of 23-27.4 and ≥27.5 kg/m2 showed lower FR of 0.66 (95% CI 0.45, 0.97) and 0.53 (0.31, 0.89), respectively. Compared to women in the lowest quartile of SFT (25-52.9 mm), those in the highest quartile of ≥90.1 mm showed lower FR of 0.58 (95% CI 0.36, 0.95). Compared to women in the lowest quartile of TBF% (13.6-27.2%), those in the upper two quartiles of 33.0-39.7% and ≥39.8% showed lower FR of 0.56 (95% CI 0.32, 0.98) and 0.43 (0.24, 0.80), respectively. Association of high BMI with reduced fecundability was particularly evident among nulliparous women. Measures of central adiposity (WC, WHR, WHtR, ABSI) were not associated with fecundability. LIMITATIONS REASONS FOR CAUTION Small sample size could restrict power of analysis.The analysis was confined to planned pregnancies, which could limit generalizability of findings to non-planned pregnancies, estimated at around 44% in Singapore. Information on the date of last menstrual period for each month was not available, hence the accuracy of self-reported menstrual cycle length could not be validated, potentially introducing error into TTP estimation. Measures of exposures and covariates such as cycle length were not performed repeatedly over time; cycle length might have changed during the period before getting pregnant. WIDER IMPLICATIONS OF THE FINDINGS Other than using BMI as the surrogate measure of body fat, we provide additional evidence showing that higher amounts of subcutaneous fat that based on the measure of SFT at the sites of biceps, triceps, suprailiac and subscapular, and TBF% are associated with longer TTP. Achieving optimal weight and reducing total percentage body fat may be a potential intervention target to improve female fertility. The null results observed between central adiposity and TTP requires confirmation in further studies. STUDY FUNDING/COMPETING INTEREST(S) This research is supported by Singapore National Research Foundation under its Translational and Clinical Research Flagship Programme and administered by the Singapore Ministry of Health's National Medical Research Council, (NMRC/TCR/004-NUS/2008; NMRC/TCR/012-NUHS/2014). Additional funding is provided by the Singapore Institute for Clinical Sciences, Agency for Science Technology and Research (A*STAR), Singapore. Y.S.C., K.M.G., F.Y. and Y.S.L. have received reimbursement to speak at conferences sponsored by companies selling nutritional products. Y.S.C., K.M.G. and S.Y.C. are part of an academic consortium that has received research funding from Abbott, Nutrition, Nestle and Danone. Other authors declared no conflicts of interest. TRIAL REGISTRATION NUMBER N/A.
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Affiliation(s)
- S L Loy
- Department of Reproductive Medicine, KK Women's and Children's Hospital, Singapore, Singapore.,Duke-NUS Medical School, Singapore, Singapore
| | - Y B Cheung
- Center for Quantitative Medicine, Duke-NUS Medical School, Singapore, Singapore.,Tampere Center for Child Health Research, University of Tampere and Tampere University Hospital, Tampere, Finland
| | - S E Soh
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.,Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore, Singapore
| | - S Ng
- Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore, Singapore
| | - M T Tint
- Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore, Singapore
| | - I M Aris
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.,Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore, Singapore
| | - J Y Bernard
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.,Early Origins of the Child's Health and Development Unit, Centre for research in Epidemiology and Statistics Sorbonne Paris Cité, Inserm, Villejuif, France
| | - Y S Chong
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.,Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore, Singapore.,Department of Obstetrics & Gynaecology, National University Hospital, Singapore, Singapore
| | - K M Godfrey
- Medical Research Council Lifecourse Epidemiology Unit, University of Southampton, Southampton, United Kingdom.,National Institute for Health Research Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton National Health Service Foundation Trust, Southampton, UK
| | - L P Shek
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.,Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore, Singapore.,Khoo Teck Puat-National University Children's Medical Institute, National University Hospital, National University Health System, Singapore, Singapore
| | - K H Tan
- Duke-NUS Medical School, Singapore, Singapore.,Department of Maternal Fetal Medicine, KK Women's and Children's Hospital, Singapore, Singapore
| | - Y S Lee
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.,Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore, Singapore.,Khoo Teck Puat-National University Children's Medical Institute, National University Hospital, National University Health System, Singapore, Singapore
| | - H H Tan
- Department of Reproductive Medicine, KK Women's and Children's Hospital, Singapore, Singapore.,Duke-NUS Medical School, Singapore, Singapore
| | - B S M Chern
- Duke-NUS Medical School, Singapore, Singapore.,Department of Obstetrics & Gynaecology, KK Women's and Children's Hospital, Singapore, Singapore
| | - N Lek
- Duke-NUS Medical School, Singapore, Singapore.,Department of Paediatrics, KK Women's and Children's Hospital, Singapore, Singapore
| | - F Yap
- Duke-NUS Medical School, Singapore, Singapore.,Department of Paediatrics, KK Women's and Children's Hospital, Singapore, Singapore.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - S Y Chan
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.,Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore, Singapore.,Department of Obstetrics & Gynaecology, National University Hospital, Singapore, Singapore
| | - C Chi
- Department of Obstetrics & Gynaecology, National University Hospital, Singapore, Singapore
| | - J K Y Chan
- Department of Reproductive Medicine, KK Women's and Children's Hospital, Singapore, Singapore.,Duke-NUS Medical School, Singapore, Singapore
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