Effect of Female Body Mass Index on Oocyte Quantity in Fertility Treatments (IVF): Treatment Cycle Number Is a Possible Effect Modifier. A Register-Based Cohort Study

Abstract

IntroductionOverweight and obese women may require higher doses of gonadotrophin when undergoing In Vitro Fertilization Treatment (IVF). Consequently, one may expect a sub-optimal oocyte retrieval in the first treatment cycle and thus a larger compensation in gonadotrophin-dose in the following treatment-cycles and a more favorable outcome. The main objective was to explore if treatment cycle number modifies the outcome when investigating the effect of female Body Mass Index (BMI) on oocyte quantity in IVF.Material and MethodsA historical cohort study was conducted on 5,342 treatment-cycles during the period 1999–2009. Exclusion criteria were missing information on BMI or treatment type. Further, women were excluded if they had ovulated before oocyte retrieval. According to baseline BMI, women were divided into four categories following the World Health Organization standards. Multiple linear regressions analyses were performed accounting for the non-independence of ≥2 cycles in a woman.ResultsStratification according to cycle number revealed a more suboptimal outcome in the first treatment- cycles than in the following cycles, suggesting a possible interaction or effect modification from cycle number or a factor related to cycle number. The median dose of total follicular stimulating hormone given to the four BMI groups could not straight forwardly explain the less optimal oocyte outcome observed in first treatment cycles. No statistically significant differences were observed in oocyte yield for underweight, overweight and obesity compared to normal weight women when analyzing all treatment-cycles. Overweight women had significantly fewer mature (MII) oocytes (p = 0.009) than normal weight women, whereas no differences was observed for underweight and obese women.ConclusionOur study suggests a possible interaction or effect modification related to treatment cycle number. Investigating the effects of BMI on IVF-results in first treatment-cycles alone should be carried out cautiously.

The impact of age and BMI on oocyte maturation and embryo development

“…The impact of age and BMI on oocyte maturation and embryo development increasing the BMI and confirm the findings of published reports with some investigator [18,19]. This result was already found in experiments conducted in mice fed with a high fat obesogenic diet, reporting oocytes with delayed maturation and decreased developmental competence in addition it has been demonstrated that these problems with oocyte function are a direct result of a mitochondrial dysfunction.…”

Association between maternal prepregnancy body mass index and pregnancy outcomes following assisted reproductive technology: A systematic review and dose–response meta‐analysis

“…In the final analysis, 105 eligible studies (19 prospective and 86 retrospective cohort studies) were included, involving more than 271,632 pregnant women (Figure 1). 14,15,28–130 The main characteristics of included studies were summarized in Table S1. In total, 100 studies reported the association between maternal BMI and CPR among pregnant women undergoing ART, among which 53 reported MR and 51 reported LBR (Table S1).…”

“…In total, 100 studies reported the association between maternal prepregnancy body weight and CPR after ART 14,15,28–55,58–80,82–117,119–122,124–130 . At per‐woman level, 54 studies, involving 109,688 pregnant women, showed an inverted J‐shaped relationship between maternal BMI and CPR ( P n < 0.01) 14,28–31,34–36,40,41,44,46,47,49,53,58,60,61,64–68,75,76,78,82,85,86,88–95,97,99,103–106,109,112–114,119,121,124,126–128,130 .…”

“…Fifty‐one studies, involving 283,386 cycles, were included in the per‐cycle level analysis 14,28,30,33–37,39,41–43,45,48,50,52–54,58,61,64,66–69,75,77,78,80,82,83,85,87,89,91,92,94–99,103–106,112,114,121,126,130 . We presented the results for both linear and nonlinear dose–response ( P n = 0.08).…”

Investigating the effect of lifestyle risk factors upon number of aspirated and mature oocytes in in vitro fertilization cycles: Interaction with antral follicle count

“…The impact regarding oocytes seems to be more pronounced; there is an increasing body of evidence demonstrating a negative correlation between number of retrieved, as well as mature (MII) oocytes in obese women implying a harmful effect of the metabolic environment on retrieved oocyte quantity and quality [27,31–34]. However, in a register- based cohort study, the effect was apparent only in first treatment-cycles, whereas no effect was observed on the following treatment-cycles (≥two) [35].…”