P–702 The effect of body weight on assisted reproduction treatment: clinical and perinatal outcomes
Authors: Campo. Dornelles V , Badalotti-Teloken I , Ribeir. Hentschke M , Deven. Trindade V , Cunegatto B , Fontour. d. Vasconcelos N , Bittencour. Antunes V D , Danie. Acker T , Pinheir. d. Costa B E , Vontobe. Padoin A , Badalotti M 
Published: August 2021

Study question

Does body weight have any effect on clinical and perinatal outcomes in assisted reproduction techniques (ART)?

Summary answer

Obesity and overweight were associated with smaller oocytes retrieved and mature number, tendency to minor pregnancy rates, and with a greater chance of macrosomic newborns.

What is known already

The body mass index (BMI) is an international measure to categorize population regarding body weight. Overweight and obesity have an established negative impact on female fertility, especially due to chronic anovulation. However, studies are inconsistent regarding body weight and ART clinical and perinatal outcomes. Some say there is no difference, others show a little or unfavorable outcomes in overweight and obese patients.

Study design, size, duration

Retrospective cohort study performed at an assisted reproductive clinic. A total of 2296 follicle stimulation cycles were included, from 1686 patients, which resulted in 2278 embryo transfers (ET). Both fresh (1942) and vitrified (354) ET cycles were included in the study. The data refers to a period from 2013- 2020 and were collected from electronic records.

Participants/materials, setting, methods

Sample was divided into groups, according to BMI (kg/m²): Group 01 (&lt;18.5, n = 30 cycles); Group 02 (18.5–24.9, n = 1630 cycles); Group 03 (25–29.9, n = 459 cycles) and Group 04 (≥30, n = 177 cycles). Data were presented as mean±SD, median (interquartile range), or percentage. ANOVA and Chi-square tests were applied, considering p &lt; 0.05. Multiple logistic regression and generalized estimating equations were performed to consider patients and cycles.

Main results and the role of chance

The mean maternal age was 35.71±3.5 years old. A statistically significant difference was observed in retrieved oocytes and mature oocytes number (MII) when groups 01 and 02 were put together (G01+G02) and compared to groups 03 and 04: (8.8 [8.5–9.2] vs 7.9 [7.3–8.6] vs. 7.2 [5.9–8.4], p = 0.005) and (6.7 [6.4–7] vs 6 [5.5–6.5] vs. 5.3 [4.3–6.3], p = 0.003), respectively. A significant linear tendency to minor pregnancy rates with higher BMI (p = 0.038), with no significant difference in pregnancy rates was found between the four groups (52.6% vs. 47.9% vs. 46.7% vs. 36.3%, p = 0.124). There was no significant difference in cumulative pregnancy, live birth rate, fertilization and implantation rates between groups. Group 04 showed a higher, but not significant, prevalence of macrosomic newborns (p = 0.110). No statistical differences regarding any other clinical and perinatal outcomes were found (prematurity, intensive care unit admission, congenital malformations, Apgar index, newborn percentile, gestational age and birthweight.

Limitations, reasons for caution

This is a retrospective study with a limited number of patients. Also there was no information on patients’ weight gain throughout pregnancy, and others clinical pregnancy diseases that could affect perinatal outcomes.

Wider implications of the findings: The study presented that the higher the weight, there seems to be a tendency towards worse outcomes of ART, especially regarding retrieved oocytes and mature oocytes number. Also, the study draws attention to the possible relationship between obesity and perinatal outcomes, also seen in spontaneous pregnancies.

Trial registration number

Not applicable