Updated by the Progyny Clinical Team — August 2025.
You may have heard of the ketogenic, or keto, diet. It’s a way of eating that is very low in carbohydrates and high in fat and protein. The goal is to put the body into a state called ketosis.
Please see below to learn more about the keto diet, and why healthcare providers generally don’t recommend it for those who are pregnant or planning to become pregnant.
Keto and your health
Carbohydrates and sugar
Carbohydrates break down into glucose, a type of sugar. Even foods that aren’t sweet, like bread or fries, turn into sugar in the body. While glucose is important for the successful development of an early pregnancy, too much sugar can cause large spikes in blood sugar and have health consequences. Over time, this can lead to:
- Insulin resistance is when cells stop using sugar effectively for energy.
- Advanced glycation end products are molecules that increase inflammation and cell damage.
These problems may lower sperm and egg quality and raise the risk of miscarriage.
Ketosis
While normally the body uses carbohydrates for energy, when you cut carbs, your body starts to burn stored fat instead. This creates ketones, which can be used as fuel. In ketosis, your body shifts from being a “sugar burner” to a “fat burner.”
Possible effects of ketosis on fertility and birth defects
Some studies suggest that eating a low-carb diet before pregnancy is linked to a higher risk of certain birth defects, such as neural tube defects. These affect the brain, spine, or spinal cord and happen in the first month of pregnancy. This link has been seen even when people take folic acid, though more research is needed.
Animal studies have similarly shown negative impacts on both heart and brain development. Other research suggests that very low-carb diets around the time of conception may be linked to a higher risk of gestational diabetes. The evidence is mixed, but it’s something health experts watch closely.
Providers also have concerns about high levels of ketones during pregnancy. Some studies have connected long-term ketosis to possible effects on a baby’s development. Because of this, medical guidelines generally do not recommend a keto diet and advise against staying in ketosis during pregnancy unless under medical supervision.
Research is limited, but one possible exception is if you’re overweight and have polycystic ovary syndrome. In that case, some studies suggest a keto diet may help improve fertility. It’s important to check with your provider before starting it.
Tips for a healthier keto approach
The keto diet is typically not recommended for those trying to get pregnant. If you try the diet, focus on nutrient-rich, high-quality foods:
- Eat vegetables, nuts, seeds, and good sources of protein.
- Choose grass-fed meats, wild-caught fish, and organic produce when possible.
- Healthy fats, such as those from avocados, olive oil, and nuts, can be part of the plan. But total calories still matter for weight management.
Remember there are different ways to do keto, and what works for one person may not work for another.
Finding the right balance
Rather than focusing on trying keto, providers often recommend focusing on cutting back on unhealthy foods and paying attention to how you feel. If you’re pregnant or planning to be, talk to your provider before making big changes to your diet.
They may also be able to refer you to a nutritionist who can ensure your goals and nutritional needs are being met. Having discussions with these experts is important because very low-carb diets may not meet everyone’s nutritional needs during this time.
If you have questions or concerns, Progyny is here for you. Please contact your Progyny Care Advocate for support.
Disclaimer: The information provided by Progyny is for educational purposes only and is not medical advice. Always consult a qualified healthcare provider for medical guidance.