Short answer: no, exercise throughout pregnancy does not increase your risk of miscarriage. In fact, it could decrease your risk
Exercise: When we find out we are pregnant, it can be really confusing on what to do or not to do. There is a lot of conflicting advice on what is safe or what could cause harm for us and our baby. Fortunately, there is a lot of research available on what is safe and beneficial for pregnancy and exercising throughout pregnancy is one of them.
If you have ever suffered from a pregnancy loss, you likely don’t know why your pregnancy ended. It can be easy to want to blame something when we don’t have an answer, and we likely will want to blame something we did or didn’t do. Maybe we worked out too hard or lifted too heavy. You may have even had someone make that statement to you after your loss, which can be so hurtful.
But, please know that you didn’t do anything to cause your miscarriage. The majority of miscarriage is due to fetal chromanol abnormality (60%). Exercise could not have had an effect, in a beneficial or adverse way, on preventing or causing these miscarriages.
What does the research say?
In a review by Parad et al, they found that “regular exercise for up to seven or more hours per week (including low-intensity and high-intensity aerobics, jogging, cycling, and swimming) is not associated with increased rates of miscarriage in the first to mid-second trimesters. Patients may continue bending and lifting at work because these activities are not associated with increased first-trimester miscarriage rates. Work that requires frequent crouching may be associated with increased miscarriage rates.”
A study that included 90,270 women from Denmark looked at exercise duration and miscarriage before 11 weeks, 11-14 weeks, 15-18 weeks, and 19-22 weeks of gestation. There was no duration or gestational age significantly correlated with miscarriage. The women in this study did all sorts of exercises such as low-impact and high-impact aerobics, swimming, jogging, cycling, and horseback riding.
There were several other studies that included 733 participants, 21551 participants, 5144 participants, and 3906 participants who found that there was no correlation between exercise and miscarriage. In a study done in Sweden, they found that there was no association between heavy lifting and miscarriage before 13 weeks of gestation! This means that you could potentially still lift heavy in early pregnancy without the risk of miscarriage.
Another common misconception is that lifting heavy could cause placental abruption, or cause the placenta to detach prematurely. But a study that looked at 663 women who had placental abruption found that only 54% of them had any type of exercise the week prior to their placental abruption. And the risk of placental abruption appears to be lower in groups that are active compared to sedentary groups.
A study from China did find that light and moderate physical activity seemed to be associated with a lower risk of miscarriage compared to sedentary work, but if their job required a lot of frequent crouching with increased intraabdominal pressure, there was an increased risk of miscarriage.
There is no increased risk of miscarriage if you exercise during pregnancy, and this included lifting heavy. Now, there are a lot of considerations on how to safely approach lifting for your own physical health (preventing injuries and pelvic floor health considerations, which we will break down in more depth in our upcoming prenatal lifting seminar on October 23rd), but there is not an exercise outside of direct contact sports or activities, that will cause harm to you or your baby.
Prenatal Complications with Contraindications to Exercise
Now, with all that said, there are some prenatal complications that exercise would not be beneficial such as severe respiratory distress, severe acquired or congenital heart disease with exercise intolerance, placental abruption, vasa previa, uncontrolled type 1 diabetes, IUGR, active preterm labor before 37 weeks gestation, severe pre-eclampsia, and cervical insufficiency.
There are some conditions that could continue to exercise with precautions, such as mild respiratory, heart disease, well-controlled type 1 diabetes, and mild pre-eclampsia, preterm premature rupture of membranes, and placenta previa after 28 weeks.
Speaking with your provider on specific exercise recommendations would be beneficial. If you are wanting to exercise more than your provider recommends, asking for specific movements that may be safe for you or for them to explain the research that supports their recommendation can be helpful.
In summary, exercising throughout pregnancy does not increase your risk of miscarriage. In some instances, it may actually decrease your risk! The majority of miscarriage is due to fetal chromosol abnormality, in which exercise could not have an effect on, neither positive nor adversely.