Planning for pregnancy involves optimizing your health in many ways, and for some, this includes considering the role of weight. While media often focuses on higher weights, both being underweight and overweight can impact fertility and the health of a pregnancy, making a balanced approach key to pre-conception care.
How weight affects ovulation and cycle regularity
Your body's ability to ovulate consistently is closely tied to its energy reserves. When body fat levels are too low, as can occur with being underweight or with excessive exercise, your body may interpret this as a state of scarcity. This can disrupt the hormonal signals from the brain to the ovaries, leading to irregular or absent ovulation (amenorrhea). The menstrual cycle can become unpredictable, making conception difficult to time.
Conversely, carrying excess weight, particularly around the abdomen, can also interfere with ovulation. Adipose tissue (body fat) is metabolically active and produces hormones, including estrogen. Higher levels of estrogen can disrupt the delicate hormonal balance needed for regular ovulation. This is often seen in conditions like Polycystic Ovary Syndrome (PCOS), where insulin resistance and elevated androgen levels, often exacerbated by higher body weight, contribute to irregular cycles and anovulation. Understanding insulin resistance in women can provide further insight into these mechanisms.
Fertility clinics and BMI thresholds
In Canada, fertility clinics often have Body Mass Index (BMI) guidelines for certain treatments, such as in-vitro fertilization (IVF). These thresholds are in place due to evidence suggesting that higher BMI can be associated with reduced success rates for fertility treatments, increased risks during pregnancy (like gestational diabetes, pre-eclampsia, and C-sections), and higher risks for the baby. While these guidelines aim to optimize outcomes, they can be a source of frustration for individuals seeking care.
The use of BMI as a primary criterion is a topic of ongoing discussion among clinicians. While it offers a standardized measure, it doesn't account for body composition, ethnicity, or individual health status. Some argue that focusing solely on BMI can delay access to necessary treatment, and that a more holistic assessment of metabolic health and individual risk factors should be prioritized. Clinicians will typically discuss these thresholds and the rationale behind them, often recommending a weight management plan if your BMI is above their established range to improve both treatment success and maternal/fetal health outcomes.
GLP-1 medications and conception: the washout question
GLP-1 receptor agonists like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) are highly effective for weight management and improving metabolic health. However, if you are planning a pregnancy, it is crucial to stop these medications well in advance of conception. This is because there is limited data on their safety during human pregnancy, and animal studies have shown potential risks to fetal development.
Clinicians will typically advise a "washout" period to ensure the medication has been fully cleared from your system before you attempt to conceive. For most GLP-1 medications, this washout period is generally recommended to be at least two months (or longer, depending on the specific medication and your individual circumstances) after the last dose. This allows time for the drug to be eliminated and for your body's systems to return to a baseline state. It is essential to have a detailed discussion with your prescribing clinician about the exact timing for stopping your medication and when it is safe to begin trying to conceive, as this guidance is specific to each medication and individual.
Contraception and weight medication
When you are taking weight management medications, including GLP-1s, it's important to discuss all forms of contraception with your clinician. A specific and interaction exists between GLP-1 receptor agonists and oral contraceptives.
GLP-1 medications can slow gastric emptying, meaning food and medications stay in your stomach for longer. This can affect the absorption of orally administered medications, including oral contraceptive pills. If an oral contraceptive is not absorbed effectively, its efficacy can be reduced, increasing the risk of unintended pregnancy. Therefore, if you are using oral contraceptives while on a GLP-1 medication, your clinician will likely advise you to use a barrier method of contraception (like condoms) or consider alternative forms of contraception that are not affected by gastric emptying, such as an IUD, contraceptive implant, or injectable contraceptives. This is a critical point that many individuals are not explicitly told about, highlighting the importance of comprehensive discussions with your healthcare provider about all your medications and family planning.
Folate, iron, and pre-conception basics
Regardless of your weight, there are fundamental pre-conception steps that are universally beneficial for a healthy pregnancy. One of the most important is ensuring adequate folate intake. Folic acid, the synthetic form of folate, is crucial for preventing neural tube defects (NTDs) in the developing baby. Health Canada recommends that all women who could become pregnant take a daily multivitamin containing 0.4 mg of folic acid, starting at least two to three months before conception and continuing throughout the first trimester.
Iron is another vital nutrient, as iron deficiency anemia is common in pregnancy and can lead to fatigue, low birth weight, and preterm birth. Your clinician may recommend an iron supplement if your iron stores are low, or advise incorporating iron-rich foods into your diet. Beyond supplements, focusing on a balanced diet rich in fruits, vegetables, lean proteins, and whole grains provides essential vitamins and minerals. Regular, moderate physical activity, sufficient sleep, and managing stress are also important pillars of pre-conception health. Discussing these basics with your healthcare provider ensures you are laying the best possible foundation for a healthy pregnancy, complementing any discussions about women's health and weight.
Common questions
Do I need to lose weight to get pregnant?
Not necessarily. While maintaining a healthy weight can improve your chances of conceiving and reduce pregnancy risks, many individuals at various weights conceive naturally and have healthy pregnancies. The focus should be on overall health, including regular ovulation, balanced nutrition, and managing any underlying conditions. If you are struggling to conceive, or have specific health concerns related to your weight, a clinician can assess your individual situation and discuss whether weight management might be beneficial for your fertility journey.
How long before trying to conceive should I stop a GLP-1?
You should stop GLP-1 medications at least two months before you plan to try and conceive. This "washout" period allows the medication to be fully cleared from your system, as there is insufficient data on their safety during human pregnancy. It is crucial to have a detailed discussion with your prescribing clinician about the specific GLP-1 medication you are taking and to follow their personalized guidance on the exact timing for discontinuation before attempting conception.
Does weight-loss medication affect birth control?
Yes, some weight-loss medications, particularly GLP-1 receptor agonists (like semaglutide or tirzepatide), can affect the absorption of oral contraceptive pills. These medications slow gastric emptying, which can reduce the effectiveness of oral birth control, increasing the risk of unintended pregnancy. If you are taking a GLP-1 medication and using oral contraceptives, your clinician will likely recommend using a barrier method of contraception (such as condoms) or switching to a non-oral form of birth control (like an IUD or implant) to ensure effective contraception.
Prefer to see someone in person?
We list medical weight-loss clinics with a physical address and match you to one for free. Licensed clinicians decide eligibility — including for any medication discussion.