The ketogenic diet, otherwise known as keto, has stepped into the spotlight over the past few years. What was once a medical prescription is now being used as a way to lose weight or try to mend hormone imbalances. But just because the diet is utilized in medical circles doesn’t mean it is the right fit for pregnancy.
The keto diet is not safe during pregnancy. Ketones produced by the mother’s body during ketosis are passed to the baby and are harmful to their neurological growth and development. For optimal health during pregnancy it is recommended to eat anywhere from 40-55% more carbohydrates than is typically allowed on the keto diet.
Keto can be a difficult topic to navigate, so in this article, I will break down its safety before and during pregnancy, along with the safety of different keto products and macros.
Why The Keto Diet Isn’t Safe During Pregnancy
Keto originated as a medical treatment for childhood epilepsy (a type of seizure disorder) and is used as a last resort when the child’s disorder is not responsive to traditional medications.
Keto patients are closely monitored by their specialized pediatric dietitian and neurologist to keep an eye on potential side effects, including keeping up with required routine lab work.
Many adults who follow keto miss this crucial monitoring, putting themselves at risk for severe vitamin deficiencies, low blood sugar, and dehydration (source: University of Chicago Medicine).
Ketosis changes how the body performs metabolism. Keto dieters eat a high percentage of their daily intake from fats, followed by protein, and finally, minimal carbohydrates. I’ll break down the macros in greater detail below.
Traditionally, carbohydrates are the body’s preferred and most readily available energy source. The human brain actually has only two different compounds it can use for energy; glucose (or carbohydrate) and ketones.
When a person eats very few carbohydrates their body has to switch how it is processing energy to create these ketones and keep the brain alive.
During pregnancy, these ketones cross the placenta and are passed to the baby (source: International Journal of Endocrinology).
For baby, the presence of ketones in utero has been shown to decrease brain size and development, lead to brain and nervous system deformity, and increase the size of the baby’s heart (source: Diabetes, Metabolic Syndrome, and Obesity: Targets and Therapies, BMC Pregnancy and Childbirth).
Due to the negative effects that ketones have on fetal growth and development, especially the development of the brain and nervous system, it is not recommended to follow the keto diet while pregnant. This is in addition to the risks presented by an unmonitored keto diet.
Following a keto diet can also create problems during labor and delivery.
A 2018 study found that women who have higher levels of ketones in their urine experienced a significantly longer duration of delivery as well as increased risk for needing an intervention (like forceps or vacuum) during vaginal delivery (source: Diabetes, Metabolic Syndrome, and Obesity: Targets and Therapies).
Of course, if you are prescribed the keto diet as a way to manage a condition, like epilepsy, be sure to be upfront with your medical providers about getting pregnant or trying to conceive. They may wish to change your plan or monitor your baby more closely.
Keto Pregnancy Macros: Safe or Not?
The keto diet is not a one-size-fits-all approach- even when used for epilepsy treatment in children!
Typically, ketosis is achieved by eating around:
- 75% of your calories from fat
- 15% from protein
- and only the remaining 5% from carbohydrates
(source: University of Chicago Medicine).
Some keto followers adjust these ratios, potentially eating more carbohydrates, however, even a modified keto with more carbohydrates is unlikely to completely prevent ketones from being produced and thus will still pose a risk to your baby’s development.
The best way to keep your baby safe from the developmentally-damaging effects of ketones during pregnancy is to eat adequate carbohydrates. The European Food Safety Authority recommends eating between 45-60% of your daily caloric intake from carbohydrates (source: Nutrients).
This way of eating is also limiting, since many foods don’t fit these parameters. This can make enjoying a night out or family dinner more difficult. Additionally, the carbohydrate content in many fruits is too high to fit within the keto plan, meaning you’ll be missing out on getting a variety of antioxidants, vitamins, and minerals from fruit, for example.
One of the studies I mentioned above, which found that the ketones were related to longer and more difficult childbirth, specifically looked at how these outcomes related to the number of ketones present.
The study found that the side effects were proportional to the number of ketones, meaning that even lower amounts still experience some risk for intervention and longer delivery (source: Diabetes, Metabolic Syndrome, and Obesity: Targets and Therapies).
Can the Keto Diet Affect Pregnancy Tests?
There are some anecdotal reports of women experiencing a ‘false positive’ pregnancy test due to being in ketosis.
While there are at-home ketone test kits where you pee on a test stick just like a home pregnancy test, being in ketosis and having ketones in your urine should not taint a pregnancy test or cause a false positive.
Pregnancy tests check for the specific hormone HcG, while ketone tests check only for the presence of ketones. Therefore being on a keto diet shouldn’t affect the results of a pregnancy test, if it’s taken properly.
Can a Keto Diet Help With Fertility or Conception?
With the rising popularity of keto has come numerous studies investigating whether or not low-carb diets can improve fertility hormones.
Fat is absolutely necessary for reproductive hormone production, as fats are actually the basis for these hormones (source: Tulane). This is one reason why women who follow very low fat or restrictive eating patterns may have difficulty conceiving, as the body doesn’t have the macronutrients it needs in order to support the reproductive process.
A review of recent scientific research found that there were significant improvements in hormone levels in sub-fertile women who followed a lower-carbohydrate diet.
It is important to note that these studies were not keto-specific, and the women only needed to eat less than 45% of calories from carbohydrates compared to keto’s more strict guideline of less than 5% (source: Nutrients).
Keto takes high-fat dieting to the extreme, with very little carbohydrate and most of your daily energy coming from fat. Including more dietary fat has the potential to aid fertility, but maintaining a very low carbohydrate intake is not necessary to experience benefits.
If you’re trying to conceive, it’s therefore unwise to follow a very low fat, or very high fat diet such as keto.
Can Keto Help Fertility in those with PCOS?
Aside from fat being a necessary component of reproductive hormones, women with PCOS are interested in keto for another reason when it comes to fertility.
PCOS and insulin resistance tend to go hand-in-hand, and chronically elevated insulin and blood sugar levels contribute to inflammation. The thought behind keto for PCOS infertility is that decreasing the amount of glucose (aka carbohydrate) entering the bloodstream will reduce insulin and inflammation levels.
In an extremely small pilot study, 2 of the 4 women who followed a medically prescribed keto diet for 6 months, followed by a non-keto yet low-carb diet were able to achieve pregnancy (source: Cleveland Clinic). The results of this study look promising, but the study is very small and doesn’t tell the full story.
Other important aspects to improving fertility in PCOS include exercise, eating antioxidant-rich foods, and ensuring adequate and regular nutrient intake which can include carbohydrates.
The latter two will help provide the body with a slow and manageable release of glucose in order to prevent the body from feeling undernourished and compensate with the release of cortisol, worsening the inflammatory cycle (source: Real Life RD).
So while there is some limited evidence that high-fat diets might boost chances of conception in women with PCOS, keep in mind that this research is new, the studies are small, and that the women in the studies were part of a program that provided close medical monitoring for safety.
Can I Have Keto Products like Keto Coffee During Pregnancy?
Keto breads, tortillas, and other grain-based products can seem like a great way to “eat keto” while still enjoying the foods you love and upping your diet variety. However, they can be a sneaky source of excessive fiber.
While fiber is necessary to keep up good digestive health, keto breads often use cellulose as a filler ingredient and to decrease the ‘net carbs’. The body isn’t able to effectively break down the cellulose and too much can lead to GI distress and abdominal cramping.
Out of curiosity, I once tried a ‘low carb’ tortilla that contained cellulose and it left me crampy and needing the restroom multiple times over the course of a single afternoon!
Keto coffee, also known as bulletproof coffee, is another keto recipe that is popular even outside of keto followers. Keto coffee is fairly simple and customizable. Its basis is black coffee with heavy cream and a fat source such as butter, coconut oil, or medium-chain-triglyceride (MCT) oil.
If you make the drink at home, there is nothing inherently unsafe about these ingredients so long as you account for any caffeine from the coffee in your daily total. You can find premade keto coffee mixes, similar to instant cappuccino or hot cocoa mixes.
These premade mixes might contain unwanted herbal ingredients or be sold as a nutritional supplement, both of which can be unsafe. If you choose to buy premade keto coffee mix be sure to read the ingredients label.
Overall, if you are considering following the ketogenic diet while expecting or looking to plan your family, hopefully this article was a helpful guide on when low carbohydrate diets can be safe and when they should be avoided.