Over the last 2 decades, the world-wide prevalence of obesity has risen dramatically. In Australia, 52% of women are overweight or obese, including 35% of women of child-bearing age (25 to 35 years of age).
Body Mass Index (BMI) is a calculation based on a person’s height and weight, and is a commonly used and simple way to quantify obesity. A person with a BMI of 25-30 is classified as overweight, and >30 is classified as obese.
Fertility rates are reduced in obese women, with a 2x longer time to achieve pregnancy compared to non-obese women. This is partly due to the reduction in normal ovulation which occurs with obesity. The success rate of fertility treatments such as IVF procedures is also reduced in obesity.
Obese individuals are also prone to polycystic ovary syndrome (PCOS), a well-recognised condition which affects ovulation and thus fertility. This is also associated with hormonal disturbances which also impact fertility. Weight loss of as little as 5% has been shown to have a beneficial effect on ovulatory function in patients with PCOS.
Pregnancy in obese women is associated with a higher risk of prolonged labour and higher rates of needing medical intervention around labour, such as induction or caesarean section.
Weight loss has been shown to be linked to improved fertility and reduced risk of pregnancy-related complications. A multitude of weight loss interventions are available, ranging from lifestyle changes to medical management to weight-loss surgery. Of these, surgery has been shown to achieve the most durable and effective long-term weight loss.
Weight-loss surgery and its effect on fertility has been studied and has been shown to lead to improved ovulatory function and fertility, as well as reducing adverse maternal outcomes.
In one published study of women with PCOS undergoing weight-loss surgery, all patients resumed normal menstrual cycles an average of 3.4 months after surgery.
Another review of a large number of studies found that in patients who had weight-loss surgery, the incidence of PCOS decreased from 45.6% to 6.8% after 12 months, and infertility decreased from 18.2 to 4.3%.
What about the effect of surgery on IVF treatment specifically? There is limited data regarding the effect of non-surgical weight-loss on fertility treatment, but a number of studies have demonstrated a positive effect. A study examining patients who had IVF before and after weight-loss surgery showed that after surgery there was a significant decrease in the total number of gonadotropin ampoules required during the IVF cycle (which also meant reduced cost and improved patient comfort from fewer injections. There was also no detrimental effect on the number of follicles or eggs retrieved.
Another study reported 5 patients who underwent bariatric surgery who conceived after their first or second IVF cycle with no complications.
It should be noted however that pregnancy in the initial 12-24 months following weight-loss surgery is not advised, as this is the period of rapid weight-loss. A pregnant woman (and her unborn child) require a relatively higher intake of nutrients which is not possible to achieve during this time. Therefore it is imperative that appropriate contraception is discussed during this period.
- Effective treatment of polycystic ovarian syndrome with Roux-en-Y gastric bypass. Eid GM et al. Surg Obes Relat Dis. 2005;1(2):77
- Does bariatric surgery improve ovarian stimulation characteristics, Oocyte yield, or embryo quality? Tsur A et al. J Ovarian Res 2014;7:116
- The impact of bariatric surgery on polycystic ovary syndrome: a systematic review and meta-analysis. Skubleny D et al. Obes Surg 2016;26(1):169-76
- In Vitro fertilization after bariatric surgery. TsurA, et al. FertilSteril2010;94(7):2812–4.
- Treatment of obesity in polycystic ovary syndrome: A position statement of the Androgen Excess and Polycystic Ovary Syndrome Society. Moran LJ et al. Fertil Steril 2009:92(6):1966-82
- Reproductive outcome after bariatric surgery: a critical review. Guelinckx I et al. Hum Reprod Update 2009;15 (2):189–201.
Mr Ben Keong MBBS FRACS