Managing weight-related infertility & pregnancy complications
Obesity increases the risk of infertility for both men and women, and increases the risk of adverse pregnancy outcomes in pregnancy. Obesity management aims to support pre-pregnancy weight loss, to normalise gestational weight gain, and to minimise maternal and offspring risks in the short- and long-term.
Key Evidence
Men living with obesity are at greater risk of impaired sperm production, erectile dysfunction and poor libido
Women living with obesity are at a greater risk of irregular ovulation and other changes to the occytes and endometrium which may reduce the chance of pregnancy
Guidelines for weight gain in pregnancy aim to balance risks of maternal obesity with the need for optimal fetal nutrition
A patient-centred approach should be taken when determining care goals for women with obesity in pre-conception, pregnancy, and post-partum. Healthcare settings should be equipped with appropriate facilities and experienced health care staff to support pregnant women with obesity
Obesity and the risk of infertility
Obesity increases the risk of infertility for women12 and men3456 Obesity is also associated with a prolonged time to pregnancy.7 The mechanisms by which obesity alters female fertility are multi-factorial and include irregular or absence of ovulation, poor quality oocytes, reduced endometrial receptivity and hormonal changes.8910
The median time to pregnancy in women of healthy weight is ~3 months compared to ~5 months in women living with obesity.11 Hence obesity increases the median time to spontaneous conception by approximately two months. In women living with obesity who require assisted reproductive care to achieve pregnancy, the rate of clinical pregnancy and live birth is lower than women of a healthy weight.1213
Male fertility is also impacted by obesity. Men living with obesity are at greater risk of suffering from impaired spermatogenesis, reduced circulating testosterone levels, erectile dysfunction and poor libido.143 Behavior change interventions (diet, exercise) and surgery for weight loss can improve fertility through increasing sex hormone levels, libido and semen quality.15
Once pregnancy is established, the short-term impacts of maternal obesity on pregnancy outcomes are well described.161718 Maternal risks include miscarriage,19 gestational diabetes,20 gestational hypertension and pre-eclampsia,1921 preterm birth (<37 weeks’ gestation), induction of labor, caesarean birth.22 Maternal obesity also increases the risk of congenital anomalies including congenital heart defects and neural tube defects.22 In women living with obesity, congenital anomalies are less likely to be detected on ultrasound, and genetic tests such as the NIPT (non-invasive perinatal testing) are more likely to yield a non-diagnostic result23. At delivery, anesthetic complications, birth trauma, and wound infections are more common in women living with obesity.1724 Rates of initiating and continuing breastfeeding are lower in women living with obesity.2526
Neonatal risks of maternal obesity include macrosomia (fetal overgrowth), jaundice and hypoglycaemia.1722 Neonates born to women living with obesity are also more likely to be admitted to the Neonatal Intensive Care Unit (NICU). Although the overall risk of neonatal death is small, this is increased in the offspring of women living with obesity compared to the healthy weight population.27
General pre-pregnancy advice for women living with obesity
Optimizing pre-pregnancy nutrition is important for all women and a nutritional assessment should be sought if there is concern about malnutrition.28 All women should be advised to take a pregnancy specific multivitamin containing iodine for 3 months pre-pregnancy until 12 weeks gestation.2829 Current guidelines recommend high dose folic acid (5mg) for women living with obesity28 which should also be commenced 3 months pre-conception until 12 weeks’ gestation. Women living with obesity should be advised to start aspirin 150mg at night and calcium 600mg PO daily from 10-12 weeks’ gestation until 36 weeks’ gestation. This reduces the risk of pre-eclampsia and of fetal growth restriction.
Guidelines for the management of obesity in pregnancy recommend that healthcare providers should discuss the risks of obesity on fertility and pregnancy.2818 Women are particularly vulnerable to experiencing weight stigma throughout pre-conception, pregnancy and post-partum, especially in healthcare settings.30 To reduce weight stigma, healthcare providers should take a supportive, non-judgmental approach and should outline the potential risks and benefits of the various weight loss strategies based on evidence, as discussed below. Pre-pregnancy weight loss programs of up to 6-12 months duration may be recommended for women aged less than 38 years. For women 38 years and older, the risks of advancing maternal age may outweigh the risks of obesity in pregnancy.31 This should be discussed with the healthcare professional.
Pre-pregnancy weight loss options
1. Support for behaviour change modification
Behaviour change modification refers to making changes predominately to diet and physical activity. The mean weight loss achieved with behaviour change interventions is 3-5kg.3233 This improves fertility but is likely insufficient to improve pregnancy outcomes in women living with obesity. For some women, focusing on lifestyle changes to support health may be more productive than a weight-centred approach. For general information on behaviour change interventions, see Lifestyle interventions for the management of overweight and obesity in adults.
2. Pharmacotherapy
Metformin may improve fertility by improving insulin resistance. It often used for women with polycystic ovary syndrome (PCOS)3435 and may be continued through-out of pregnancy unless a fetus is growth restricted. Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) such as Semaglutide are contraindicated during pregnancy and breastfeeding.36 However, some women use these medications to achieve weight loss and improve glycaemic control prior to pregnancy.37 To avoid exposure in early pregnancy, the drug should be ceased five half-lives before conception (ie. the half-life of Semaglutide is 7 days so it should be stopped 5-6 weeks before pregnancy). If inadvertent pregnancy occurs while on these agents, the drug should be ceased immediately. While there is no evidence of teratogenicity due to early pregnancy exposure38, the impact of early pregnancy exposure has not been assessed39.
3. Bariatric surgery
Bariatric surgery results in a greater mean weight loss than behaviour change modification. Bariatric surgery prior to pregnancy in women living with obesity improves fertility and reduces rates of gestational diabetes and gestational hypertension/pre-eclampsia.404142 However, there is an increase in the rate of small-for-gestational-age offspring, and potentially an increased risk of neonatal death.43 These adverse outcomes likely reflect malnutrition rather than the weight loss per se. Women who have had bariatric surgery are recommended to delay conception for at least 12-18 months due to the risk of adverse pregnancy outcomes secondary to malnutrition.44 Women who have had bariatric surgery should also remain under the care of a dietitian prior to and during pregnancy.184428
Regardless of the method of weight loss, women living with obesity should aim for a period of weight maintenance prior to conception.22
During pregnancy: recommended gestational weight gain
During pregnancy, women should not intentionally lose weight.45 Catalano et al. has shown that women living with obesity who gain inadequate weight during pregnancy (<5kg) have a significantly increased risk of small-for-gestational-age infants.46 These infants carry the same long-term metabolic risks as large-for-gestational-age infants.47 A meta-analysis found for women living with obesity, both low and high weight gestational gain were associated with increased risk of gestational diabetes, gestational hypertension, pre-eclampsia, preterm birth and large for gestational age.48 Women should therefore be supported to gain weight during pregnancy within the Institute of Medicine guidelines (Table 1 and Table 2). This will balance the risks of insufficient weight gain in pregnancy with the risks posed by maternal obesity.22
Table 1: IOM recommendations for weight gain in pregnancy
*Calculations assume a 0.5-2kg weight gain in the first trimester. Note: The recommended weight gain ranges are indicative only and provide suggested limits rather than specific goals.
Sources: Australian pregnancy care guidelines (2025) based on (IOM 2009)
| Pre-pregnancy weight category | Pre-pregnancy BMI (kg/m2) | Recommended gestational weight gain (kg) | Recommended weight gain* in 2nd & 3rd trimester (kg/week) |
|---|---|---|---|
| Underweight | < 18.5 | 12.5–18.0 | 0.51 (0.44–0.58) |
| Healthy weight | 18.5–24.9 | 11.5–16.0 | 0.42 (0.35–0.50) |
| Overweight | 25.0–29.9 | 7.0–11.5 | 0.28 (0.23–0.33) |
| Obese | > 30.0 | 5.0–9.0 | 0.22 (0.17–0.27) |
Table 2: Recommendations for weight gain in pregnancy among women from an Asian background
*Calculations assume a 0.5-2kg weight gain in the first trimester. Note: The recommended weight gain ranges are indicative only and provide suggested limits rather than specific goals.
Sources: Australian pregnancy care guidelines (2025) based on (IOM 2009) and Asian BMI cut-offs
| Pre-pregnancy weight category | Pre-pregnancy BMI (kg/m2) | Recommended weight gain (kg) | Rates of weight gain* 2nd & 3rd trimester (kg/week) |
|---|---|---|---|
| Underweight | < 18.5 | 12.5–18.0 | 0.5 |
| Healthy weight | 18.5–22.9 | 11.5–16.0 | 0.4 |
| Overweight | 23.0–29.9 | 7.0–11.5 | 0.3 |
| Obese | > 27.5 | ≤ 7.0 | - |
Recommendations for pregnancy and delivery
Maternity care facilities should have well-defined pathways for the care and management of pregnant women with obesity. In some cases, this may mean that a woman needs to be transferred to an alternative hospital that has appropriately experienced health care staff and bariatric equipment to care for pregnant women2228 This is particularly the case for over with a body mass index >50k/m2.
There can be challenges with the assessment and monitoring of pregnant women living with obesity. Ultrasound visualisation may be poor and the assessment less accurate in women with obesity,22 but is likely superior to clinical assessment.49 A third trimester fetal growth ultrasound should be offered to all women with obesity.50
There is no consensus on the optimal timing of birth for women living with obesity.285152 Awaiting spontaneous labour after the due date may increase the risk of macrosomia and stillbirth.22 Women with a body mass index >50kg/m2 may be offered a delivery date prior to their due date. Women living with obesity should be advised of the increased risks of emergency Caesarean section compared to both an elective Caesarean section and a vaginal delivery. As part of delivery care planning, healthcare providers should discuss the various options and the risks and benefits of each to help women with obesity make an informed decision on mode of birth.2842
Post-partum recommendations
Given the lower rates of breastfeeding in women living with obesity, support and advice with initiating and continuing breastfeeding should be offered.1828 Healthcare providers should be aware of the relationship between mental health and obesity, and provide appropriate, screening, care and referral.18
Women living with obesity should continue to be offered dietary and physical activity care to support their health and weight management, including being informed of the benefits of weight loss between pregnancies or limiting further weight gain.1828 Women living with obesity prior to pregnancy are more likely to gain excessive weight in pregnancy and to maintain this additional weight in the long term.53 Recommendations advise that women living with obesity aim to return to their pre-pregnancy weight within 12-18 months of delivery.46
Content for this page was written by Dr Sarah Price, NHMRC Fellowship-Senior Research Fellow, University of Melbourne; and reviewed by Dr Jade Eccels-Smith, Bond University and Josephine Marshall at the Global Centre for Preventive Health and Nutrition at Deakin University. For more information about the approach to content on the site please see About | Obesity Evidence Hub.