Is there really an Ozempic baby boom? The unexpected ways GLP-1s could influence fertility.
These medications may be influencing fertility in ways scientists are only beginning to understand.
When the GLP-1 medications were first approved for weight loss, “I got pregnant on Ozempic” headlines quickly followed. People spoke about sudden unintended pregnancy, and “Ozempic babies” entered the lexicon.
Could a medication meant to combat diabetes and shrink waistlines also boost fertility? For some, especially people struggling with infertility, these accounts sparked hope. For others, they raised new fears: Could these blockbuster drugs make birth control less effective?
The real story is not so simple. While anecdotes abound, scientists are still untangling how GLP-1 receptor agonists—drugs like Ozempic, Mounjaro, Zepbound, and Wegovy—affect reproduction and weight loss. People with specific conditions may benefit from the improved insulin control and metabolic health the drugs provide—and fertility benefits may follow. But for others, fertility reflects how weight, hormones, and metabolism work together—under the quiet pressure of time.
Can Ozempic overcome your birth control?
Glucagon-like peptide-1 receptor agonists (GLP-1s) mimic the actions of a natural hormone that helps control blood sugar and appetite. These receptors are scattered throughout the gut, brain, and pancreas—so the effects ripple widely through the body. The most apparent effect for anyone taking them, though, is that the drugs slow gastric emptying—making food stay in the stomach longer and prolonging the full feeling it provides. The result is often reduced hunger and thirst, improved insulin control, better cardiovascular markers, and, for many people, substantial weight loss.
But does starting Ozempic really throw off birth control? “I'm not aware of any publications that actually report changes in pregnancy rates themselves,” says Jessica Skelley, a pharmacist at Samford University in Birmingham, AL. But “when you orally ingest a medication, the drug passes through the stomach to the small intestine, which is actually where most drugs are absorbed,” she says. More time in the stomach could mean there’s a delay in drug absorption.
(Birth control pills: What you should and shouldn’t worry about.)
To find out, in 2024, Skelley and her colleagues searched the literature and looked for papers that measured how much oral birth control got into people’s bloodstream while they were on GLP-1 drugs. They found that semaglutide (Ozempic, Rybelsus, Wegovy) did not reduce oral contraceptive concentrations in blood or significantly delay absorption. Other GLP-1s like exenatide (Byetta, now discontinued), liraglutide (Victoza), and dulaglutide (Trulicity) reduced plasma levels of oral contraceptives by up to 45 percent and delayed absorption by up to 3.5 hours, though not enough to cause the birth control to fail.
“Semaglutide causes the stomach to empty more slowly and may impact how the body absorbs any oral medications taken at the same time,” Novo Nordisk, maker of semaglutide, said in a statement. “We recommend all patients considering taking any oral medications at the same time as semaglutide make decisions cautiously and alongside a healthcare provider.”
Tirzepatide, marketed as Mounjaro and Zepbound, was a different story. It reduced plasma hormone levels by up to 66 percent and delayed the maximum effect by up to 4.5 hours. “It was with the five-milligram dose, which is one of the lower doses of tirzepatide,” Skelley says. “Even that lower dose showed a pretty profound impact.”
The reason, Skelley explains, is that tirzepatide isn’t just a GLP-1 drug—it also activates another receptor, called the glucose-dependent insulinotropic polypeptide receptor. That dual action makes it especially potent. The result is fewer side effects than the other GLP-1 agonists, along with more weight loss and better insulin control, Skelley notes.
Still, in the process, “you do get more delay in gastric emptying, which is what leads to the drug interaction between tirzepatide and oral hormonal contraceptives.” The FDA recommends that people using the drug also use backup birth control when starting injections and every time they increase their dosage.
In a statement, Eli Lilly, maker of tirzepatide, noted that “the Zepbound and Mounjaro U.S. FDA-approved labels, explain that tirzepatide may reduce the efficacy of oral hormonal contraceptives due to delayed gastric emptying. Patients using oral hormonal contraceptives are advised to switch to a non-oral contraceptive method or add a barrier method of contraception for four weeks after initiation with tirzepatide and for four weeks after each dose escalation.”
Still, experts caution against the idea that the drugs make people more fertile. Birth control is probably “a little bit more likely [to fail], if you're on something that decreases absorption,” says Christina Boots, a reproductive endocrinologist and infertility specialist at Northwestern University in Chicago, Illinois. But “did you also start exercising more? Did you also eat healthier? Was that time point different [in] other ways, or was it just the medication that you went on?”
Can GLP-1 drugs help people with PCOS get pregnant?
Of course, that only applies to people who don’t already have fertility challenges. Polycystic ovary syndrome (PCO or PCOS) is “the most common endocrine condition that happens in women,” says Nanette Santoro, professor and chair of obstetrics and gynecology at the University of Colorado, Boulder, potentially affecting up to 15 percent of the female population. (Santoro has consulted with pharmaceutical companies on drugs involving reproductive health, including Bayer, Novo Nordisk, Astella, and Perigo.)
As its name suggests, PCOS often begins in the ovaries—and it’s one of the most common causes of infertility. Patients don’t ovulate regularly and typically produce more androgens (such as testosterone) than they should. Many also have insulin resistance, Santoro notes. “Women with PCO tend to gain weight,” she says. “And the more weight they gain, the worse their fertility outcomes are. So PCO and obesity is a pretty clear relationship.”
(You can’t detox your uterus—debunking popular myths about PCOS.)
For people who experience insulin resistance and weight gain as part of their PCOS, Boots notes, controlling insulin—and losing weight in the process—can reduce symptoms, no matter what the drug or method is. “About 20 percent of women who go on Metformin [another diabetes drug that targets insulin resistance] will have improved ovulation with it,” Boots says.
GLP-1s, she says, might have similar effects “because most women with PCOS, their obesity is so tightly linked to insulin resistance, I think they benefit more than just the average person with obesity. GLP-1 drugs do appear to help some of the metabolic issues, and may help make menstruation more regular in PCOS patients.
Unfortunately, she says, there’s no good evidence that GLP-1s, especially the newer drugs like Mounjaro, actually improve ovulation or pregnancy odds in people with PCOS. Or at least not yet. “We have all this understanding of the physiology and understanding of these other studies that have had weight loss or have had improved insulin resistance, and you see improvement,” Boots says. “So now that you have this cool drug that does both of those things much better than anything else, I suspect we're going to see a lot of improvement, and studies will follow.”
Fertility is more than body size
Even for people without PCOS, weight may play a role in fertility under certain conditions. Some research suggests that for people with insulin resistance, metabolic improvements can help restore regular ovulation—but the evidence remains mixed. As people get larger, “there’s a relative change in the ability to get pregnant every month,” Santoro says.
In her own studies, Santoro has found that hormones associated with fertility tend to decrease as people increase in size. The same holds at the opposite end of the scale. Extreme low weight is also associated with reduced hormone levels and loss of menstruation.
Still, size alone doesn’t determine fertility. “I hate the stigma that you’re infertile because you’re big,” Boots says. “I just don't want that to be out there. There’s already enough guilt about being in a bigger body. There's enough guilt about not being able to get pregnant.”
(The unexpected health benefits of Ozempic and Mounjaro.)
In some higher-weight individuals, weight loss can change pregnancy odds. “I did some studies looking at pregnancy after bariatric surgery,” says Kate Maslin, a research fellow in maternal and child health at the University of Plymouth in England. “In that population, it was not uncommon for people to inadvertently get pregnant because they had lost such a significant amount of weight that their ovulation kind of recalibrated.” If people experienced similar rapid weight loss due to GLP-1s, she says, “There is potential for them to start to re-ovulate.”
Yet results across weight-loss studies are inconsistent. In a 2022 study, Santoro found that after 16 weeks of exercise, meal control, and the over-the-counter drug orlistat (Alli), “we did not see an improvement in pregnancy rate.” In a similar 2016 study in the Netherlands, the weight-loss intervention resulted in a slight decrease in the pregnancy rate. A 2025 review of 12 small trials suggested modest gains in natural conception—but not in IVF outcomes.
The path to fertility care is further complicated by how doctors approach weight. Jacquelyn Gill, a paleoecologist at the University of Maine in Orono who is in a larger body, sought help with fertility after struggling to conceive for a year in 2014. The first doctor she saw, she says, told her, “why don’t you take a year, lose as much weight as you can, and then come back and we’ll talk.” They didn’t even perform any tests.
Gill, then 33, says she was offered no other guidance beyond diet and exercise. “You want people to be healthy,” Santoro says, “but are we stressing women out by forcing them to lose weight and to go on a pretty rigorous weight-loss protocol that’s actually not helping?” GLP-1 drugs may offer a more effective alternative, she says, promoting weight loss with less psychological strain.
Still, research remains scarce. “There are zero. Let me repeat that, zero studies looking at the impact of GLP-1 receptor agonist, and anything related to fertility or menstruation and women without PCOS,” says Zaher Merhi, a reproductive endocrinologist with Rejuvenating Fertility Center and Albert Einstein College of Medicine. Online, he notes, people often assume the drugs improve fertility. “There are anecdotal stories, ‘Oh my friend took it and got pregnant the next month,’ and stuff like that,” he says. “I think we're craving something that's really magical, right?”
But studies of pregnancies and hormones aren’t enough to prove a connection, he says. He wants to see “the ovarian function and egg quality, or uterine function and biopsy of the lining. I'm talking about the cellular level, not just the hormonal level.”
Do GLP-1 drugs affect male fertility, too?
It is all too easy to focus entirely on female anatomy when thinking about fertility. But “about half the time there's difficulties in an infertile couple, it is a male factor that's leading that,” says Michael Eisenberg, a reproductive urologist at Stanford Medical School. Most conditions that harm overall health also affect male reproduction, he explains. Diabetes, for instance, can reduce semen quality and impair sexual function, while high blood pressure can have similar effects.
“The general thing I tell everybody, [if] it affects your heart, [it] can also affect your reproduction.”
Just as there is an association between body size and reproductive hormones in female bodies, “there is an association between body mass index and semen quality,” Eisenberg says. Extra weight may dull the body’s responsiveness to the hypothalamic–pituitary–gonadal axis, the hormone circuit that regulates reproduction. Or it may simply raise testicular temperature.
(Sperm counts worldwide are plummeting faster than we thought.)
“The testicles are outside the body, because they need to be cooler, and then having just more insulation, you know, down there specifically is thought to warm up the area, [to] make spermatogenesis less efficient.” Chronic inflammation could also play a role.
But whether GLP-1s have positive or negative effects on sperm count, sexual function, or anything else is not well known. In a 2022 study funded by Novo Nordisk, weight loss followed by exercise or a GLP-1 drug improved sperm count, and there doesn’t seem to be much risk. But studies are “very limited,” Eisenberg says. “Just a handful of studies, you know, that don’t support a negative effect.”
Is Ozempic safe to use during pregnancy?
In some cases, GLP-1s might help people get pregnant, but once someone is expecting, it’s a different story. Studies in animals have shown that high doses of GLP-1 drugs cause fetal problems, in part because the drugs reduce appetite so much. “The animal mothers are not consuming sufficient calories,” says Maslin. “There is reduced fetal weight and kind of reduced ossification of the bones and potentially congenital abnormalities in the offspring.” These problems have not been observed in humans, but there have also been no deliberate studies of their effects during pregnancy.
Right now, doctors usually suggest going off the drugs before trying to conceive. “We're, using calories as we’re growing a human,” Boots says. “We shouldn’t be starving our bodies.” Because the drugs are so new, she notes, scientists also don’t know how the resulting child’s metabolism might be impacted.
In a statement, Novo Nordisk, maker of the GLP-1 drug semaglutide, noted, “For Wegovy® specifically, animal studies suggest there may be risks to the fetus, and weight loss during pregnancy offers no benefit and may cause harm. If a pregnancy is recognized, patients should stop Wegovy® and discuss next steps with their healthcare provider. Available clinical and postmarketing data are still too limited to determine whether semaglutide is associated with major birth defects, miscarriage, or other adverse outcomes.”
When weight loss delays fertility care
The confluence of weight and fertility is a painful one to navigate. Gill tried and failed to lose weight for years, while still trying to conceive. “I did everything that I that was in my control,” she says. “I was avoiding cold cuts. I was avoiding any soy because that might mess with your hormones, and then you can't get pregnant. I was eating a healthy diet. I was exercising. I was avoiding hot baths, like everything that I could do, while also managing your stress. Because, you know, you can't get stressed.”
Meanwhile, she says, doctors refused to address any underlying causes of her infertility, including adenomyosis—a thickening of the uterine wall that can impact fertility. One fertility doctor told her, “it would be unethical for me to treat you with your BMI.”
(Does a woman’s fertility really plummet at age 35?)
By the time Gill found a doctor who listened and assisted, she had lost nearly four years. Despite further treatment with intrauterine insemination and a gestational carrier, she was unable to conceive. The experience—being dismissed for her weight, dealing with the pain of her adenomyosis, infertility, dieting, and more—was physically and emotionally grueling. “We are human beings who are going through one of the hardest things we will ever go through,” she says.
When people are seeking treatment for infertility, they may be prevented by weight cutoffs at clinics or by doctors like Gill’s telling them to lose weight without overriding other interventions. “Overweight and obese women are not treated equally in the fertility world,” Merhi says.
Sometimes, he notes, other clinicians won’t even check for fertility problems first—they will only see someone’s size. “When they go to have fertility evaluation, the first thing they say is, ‘go lose weight and come back to me in a year.’ Why don't you do the basic workup for her and her partner, check the sperm?” he asks.
Since many clinics have weight cutoffs before they will even treat a patient, some patients might pursue GLP-1s to meet the requirements, Merhi adds.
That delay is even more fraught as people have children later in life. “For some women, their [egg] reserve and their ovaries may go down over that period of time,” Santoro says. “Sending people away to go and lose weight without giving them a lot of effective tools is really almost cruel.”Merhi adds, “Patients can go into menopause, or they tell them, ‘Now we have age cut off, and now you're too old.’”
Gill notes that the drugs don’t work for everyone. “It just feels like the celebrity experience that we hear about, where it's like, ‘oh, wow, in one year, this person went from like 300 pounds to like 100 pounds,’ I think that's what people expect,” she says. “If people are told, ‘oh, take this,’ and then that's not how it works for them, then they've lost precious time.”
That’s why, Maslin says, it is important to truly understand whether GLP-1 drugs have a strong effect on fertility or not. Someone’s ability to become a parent is in the balance, which means research that speaks to people’s experiences, as well as clinical trials. “You really need to speak to people and understand their experiences, their motivations and their barriers to using the medications or not using the medications,” she says. “This is going to be a very individual dilemma for people to face.”
Patients facing it deserve compassion no matter what body they are in, says Gill. “There are a lot of people who will do anything to have a baby,” she says. “And those people are vulnerable and should be treated with respect and care.”
