Your body views exercise as a form of stress and this signals to the hypothalamus in the brain it might not be a safe time for reproduction. A cascade of changes, such as lowered levels of oestrogen and progesterone can occur which leads to menstrual cycle changes, failure to ovulate or amenorrhoea (complete loss of periods) in some women.
However, this can be fixed with a few tweaks to your training. Try swapping your intense interval training sessions, heavy weights, or long runs for more moderate workouts like pilates, Yoga, brisk walking, or swimming for 30 or 60 minutes, and include one or two rest days for recovery.
TOO LITTLE
Of course, not enough exercise can have its own impact on fertility. If you are generally sedentary, increasing your exercise to meet the guidelines of 30 minutes a day can help boost circulation, lower stress levels and improve your metabolism - all of which contribute to the production of healthy eggs.
Daily physical activity alongside a healthy diet filled with whole foods can also help those who are overweight achieve a healthy BMI of between 18.5 and 24.9. This weight range is associated with optimal reproductive function and reduces your chance of complications, such as gestational diabetes, during pregnancy.
Try activities such as water aerobics, stationary cycling, rowing, or weight training, which are low impact so are kind to your joints, yet still provide an effective workout.
DURING IVF
Optimising the success of your IVF is most important, so exercise may take a back seat during this time. This is not because you shouldn't exercise; a 20 - 30 minute walk is still beneficial and totally safe, but mostly because you probably won't feel like it due to side effects of the fertility drugs.
However, if you do decide to exercise, it's best to avoid vigorous activity or heated exercise classes like Bikram yoga, which may elevate your core temperate too high, with some research suggesting a link to neural tube defects. Your best bet is to exercise early in the morning or late in the evening during summer, or take your workout indoors at the gym, making sure to wear comfortable clothing to stay cool.
Getting the dose of physical activity "just right" is definitely an important factor in the fertility equation, so talk to your doctor or an exercise physiologist if you want some guidance on what workouts are best to get a baby on board.