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Reproductive outcomes may be improved by weight loss prior to in vitro fertilization (IVF), according to a recent study published in the Annals of Internal Medicine.¹

The results highlighted increased pregnancy success in women with pre-IVF weight loss, especially in unassisted conception. However, live birth outcomes were not available.¹

“Further high-quality clinical trials testing different weight loss interventions, particularly those known to achieve greatest weight losses (e.g. low-energy total diet replacement programs) are needed,” wrote investigators.¹

Assessing reproductive outcomes

The study was conducted to assess reproductive outcomes following pre-IVF weight loss.² Five electronic databases were search for randomized controlled trials (RCTs) including women with obesity who were offered weight loss prior to IVF. Those published through May 27, 2025, were eligible for inclusion.

Low-energy diets, an exercise program alongside healthy eating advice, and pharmacotherapy alongside diet and physical activity device were considered as weight loss interventions. All participants were seeking IVF with or without intracytoplasmic sperm injection treatment for infertility.²

RCTs underwent dual independent screening, with those included having relevant data extracted and undergoing assessment for risk of bias. Pregnancy and live birth rates were reported as the primary outcomes.²

There were 1921 participants across 12 RCTs included in the final analysis. These patients were aged at least 18 years old and had a body mass index (BMI) of 27/kg2.¹ They were often in their early 30s, and the median BMI was 33.6 kg/m2.

Pregnancy and live birth outcomes

Of RCTs, 7 had a high risk of bias.² However, an association with moderate certainty between weight loss prior to IVF and total pregnancy rates was reported, with a risk ratio (RR) of 1.21 from 11 studies.

Similarly, an RR of 1.47 across 10 studies was reported for pregnancy following unassisted conception. However, there was not certain evidence about the impact on pregnancies from IVF alone.²

The RR for pregnancy loss with moderate certainty across 8 studies was 1.05 from weight loss interventions, indicating no significant impact. Similarly, an RR of 1.15 was reported for live birth rates across 9 studies, but the certainty of evidence was very low, making the impact of weight loss interventions on this outcome unclear.²

Overall, the data indicated increased odds of pregnancy, especially without assisted conception, from weight loss interventions prior to IVF. However, investigators noted the study was limited by small study sizes, high risk of bias, and heterogeneity.²

Public support for IVF

The demand for adequate IVF care has been indicated by a 2024 survey showing increased public support for this method of conception.³ Of respondents, 67% expressed a belief that IVF coverage should be offered by health insurance plans, with only 7% expressing opposition.

Investigators highlighted barriers to IVF coverage such as limited access among military service members and coverage only being provided to federal employees by a few available insurance plans. The American Society for Reproductive Medicine recommended patients with regular, unprotected intercourse and no known etiology for infertility undergo evaluation.³

References

1. Losing weight before IVF may increase chance of pregnancy. American College of Physicians. August 11, 2025. Accessed August 15, 2025. https://www.eurekalert.org/news-releases/1093687
2. Michalopoulou M, Ann Jebb S, Hobson A, et al. The effect of weight loss before in vitro fertilization on reproductive outcomes in women with obesity: a systematic review and meta-analysis. Annals of Internal Medicine. 2025. doi:10.7326/ANNALS-24-01025
3. Krewson C. Survey shows growing support for IVF coverage in US health care. Contemporary OB/GYN. April 25, 2025. Accessed August 15, 2025. https://www.contemporaryobgyn.net/view/survey-shows-growing-support-for-ivf-coverage-in-us-health-care.

A patient with type 1 diabetes has begun producing his own insulin after receiving a transplant of pancreatic cells.

For the first time in humans, these islet cells have been genetically edited so they wouldn’t be rejected by the patient, removing the need for immunosuppressant drugs.

Type 1 diabetes usually begins when the immune system mistakenly attacks the islet cells in the pancreas, which are responsible for producing insulin. The condition is usually managed with a careful diet and regular insulin injections, but an emerging treatment involves replacing the damaged islet cells with functional ones.

Related: New Treatment May Cure Severe Type 1 Diabetes, Study Finds

In a new proof-of-concept study, a 42-year-old male patient, who had had type 1 diabetes since the age of 5, received a transplant of islet cells from a healthy donor. The cells were delivered through a series of injections into the muscle of his forearm.

Over the next 12 weeks, the cells successfully produced insulin in response to glucose spikes, such as after meals. But the most important aspect is that the patient didn’t require immunosuppressants.

Normally, the immune system will recognize the transplanted cells as foreign and destroy them, rendering the therapy ineffective. To get around that, patients are given drugs that suppress their immune system. That solution works, but leaves the patients vulnerable to infections and other illnesses.

So, before the cells were implanted, three genetic edits were made using the CRISPR tool. Two edits reduced the amount of particular antigens that adaptive T cells use to identify foreign objects. The third boosted production of a protein called CD47, which in turn blocks innate immune cell responses.

Not all of the gene edits were successful, but in a way that provided an intriguing control group. Cells with no successful edits were killed off by T cells within a few weeks, while those that knocked out the antigen production were still wiped out by natural killer cells and macrophages.

Only those with three successful edits survived, and thankfully there were enough of them in the graft to remain functional.

The technique had previously shown promise in tests in monkeys and mice, but this marks the first time it has been attempted in humans. Similar studies in humans have shown promise, but always with the help of immunosuppressant drugs, which bring their own complications.

Last year, doctors reported that a young woman in China received a transplant of insulin-producing cells grown from her own stem cells. Within four months, her body was able to produce enough insulin to stay within a safe blood glucose range for over 98 percent of the day.

The researchers on the new study say that their method could not only make for more effective, safer treatments for diabetes, but could be applied to other types of cells, reducing the need for immunosuppressants with other transplants.

The research was published in The New England Journal of Medicine.