The role of female obesity on in vitro fertilization outcomes

Abstract

The aim of this review is to analyze the role of obesity on fertility outcome in women undergoing in vitro fertilization (IVF) with respect to clinical or live birth rates and pregnancy loss rates. Despite findings from several earlier and newer studies that obesity does not adversely affect pregnancy outcome in women attempting conception, numerous reports from mostly recent studies suggest that obesity undoubtedly impairs IVF outcomes. Obesity impairs ovarian responsiveness to gonadotrophin stimulation, requiring higher doses of medication, increased risk of cycle cancelation, pre-term delivery, low birth weight or miscarriage, and decreases implantation, clinical pregnancy or live birth rates compared to women of normal weight. The mechanisms underlying the adverse effects of female obesity on IVF outcome may be primarily explained by functional alterations to the hypothalamic-pituitary-ovarian axis. Additionally, obesity appears to affect deleteriously the number and quality of oocytes or embryos, and impairs endometrial decidualization which is necessary for uterine receptivity. Nevertheless, attaining normal body weight by the use of lifestyle modifications, including a healthy diet and exercise over time of several months before and during an IVF treatment, may be successful in achievement of gradual and sustainable weight loss with improvement of IVF outcome.

Chinese abstract

本综述的目的是分析女性肥胖对体外受精（IVF）结局的影响, 包括临床妊娠、活产率、流产率等。尽管有一些早期与较新的研究结果表明, 肥胖对试图怀孕的女性妊娠结局没有负面影响, 但大多数近期的研究显示, 肥胖无疑会影响IVF结局。与体重正常的女性相比, 肥胖会降低卵巢对促性腺激素的反应性, 需更高的药物剂量, 增加了周期取消率、早产率、低出生体重率及流产率, 降低了胚胎植入率、临床妊娠率及活产率。女性肥胖对IVF结局的不良影响的机制可能与下丘脑-垂体-卵巢轴的功能改变有关。此外, 肥胖也许对卵母细胞或胚胎的质量与数量产生不利影响, 并且损伤子宫内膜容受性必需的蜕膜化。尽管如此, 通过生活方式改变获得正常体重, 如IVF治疗前几个月与治疗期间进行健康的饮食和运动, 可逐渐获得并维持体重减轻, 改善IVF结局。

Keywords:

• Female obesity
• IVF
• underlying mechanisms
• pregnancy outcome

Disclosure statement

The authors report no declarations of interest.