Abstract
Objective
This study aims to determine whether emergency contraceptive pills (ECPs) are less
safe and effective for women with obesity compared with those without obesity.
Study design
We searched PubMed for articles through November 2015 regarding the safety and effectiveness
of ECPs [ulipristal acetate (UPA), levonorgestrel (LNG) and combined estrogen and
progestin] among obese users. We assessed study quality using the United States Preventive
Services Task Force evidence grading system.
Results
We identified four pooled secondary analyses (quality: poor to fair), two of which
examined UPA and three examined LNG formulations. Three analyses pooled overlapping
data from a total of three primary studies and demonstrated significant associations
between obesity and risk of pregnancy after ECP use. One analysis reported a 4-fold
increased risk of pregnancy among women with obesity (BMI≥30 kg/m2) compared with women within normal/underweight categories (BMI<25 kg/m2) after use of LNG ECPs [odds ratio (OR) 4.4; 95% confidence interval (CI) 2.0–9.4].
Further analysis of the same LNG data found that, at an approximate weight of 80 kg,
the rate of pregnancy rose above 6%, which is the estimated pregnancy probability
without contraception; at weights less than 75 kg, the rate of pregnancy was less
than 2%. Two analyses examining UPA suggested an approximate 2-fold increased risk
of pregnancy among women with obesity compared with either normal/underweight women
or nonobese (BMI<30 kg/m2) women (OR 2.6; 95% CI 0.9–7.0 and OR 2.1; 95% CI 1.0–4.3, respectively), but CIs
were wide. Finally, the fourth secondary analysis pooled data from three separate
randomized controlled trials on LNG ECPs and found no increase in pregnancy risk with
increasing weight or BMI and found no consistent association between pregnancy and
both factors when adjusted for other covariates.
Conclusion
While data are limited and poor to fair quality, findings suggest that women with
obesity experience an increased risk of pregnancy after use of LNG ECP compared with
those normal/underweight. Women with obesity may also experience an increased risk
of pregnancy compared with women without obesity after use of UPA ECP, though differences
did not reach statistical significance. Providers should counsel all women at risk
for unintended pregnancy, including those with obesity, about the effectiveness of
the full range of emergency contraception options in order for them to understand
their options, to receive advanced supplies of emergency contraception as needed and
to understand how to access an emergency copper intrauterine device if desired.
Keywords
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Article info
Publication history
Published online: May 24, 2016
Accepted:
May 18,
2016
Received in revised form:
May 17,
2016
Received:
March 3,
2016
Footnotes
☆Financial Disclosures: None.
☆☆Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the US Centers for Disease Control and Prevention.
Identification
Copyright
© 2016 Published by Elsevier Inc.
