We investigated the association between exercise during pregnancy and risk of miscarriage among more than 90,000 pregnant women. Information on exposures was obtained by means of computer-assisted telephone interviews. A relation was found between the amount of exercise and the risk of miscarriage with the risk of miscarriage rising stepwise by the amount of exercise performed. Exercising 1–44 minutes/week was not associated with an increased risk of miscarriage. The largest risk estimate was seen in women with miscarriages in 11–14 weeks who exercised more than 419 minutes/week (hazard ratio = 3.7). Particularly "high impact exercise" was associated with an increased risk of miscarriage. No association was seen between exercise and risk of miscarriage after 18 weeks of gestation.
http://onlinelibrary.wiley.com/doi/10.1111/j.1471-0528.2007.01496.x/pdf
A total of 2,232 patients were prospectively enrolled before undergoing their first cycle of IVF for the treatment of infertility from 1994-2003 at three IVF clinics in the greater Boston area. The primary IVF outcomes of interest included successful live birth and four points of cycle failure: cycle cancellation, failed fertilization, implantation failure, and miscarriage. RESULTS: Women who reported exercising 4 hours or more per week for 1-9 years were 40% less likely to have a live birth (odds ratio 0.6) and were almost three times more likely to experience cycle cancellation (odds ratio 2.8) and twice as likely to have an implantation failure (odds ratio 2.0) or miscarriage (odds ratio 2.o) than women who did not report exercise. In general, women who participated in cardiovascular exercise had a 30% lower chance of successful live birth (OR 0.7) than women who reported no exercise. CONCLUSION: Regular exercise before in vitro fertilization may negatively affect outcomes, especially in women who exercised 4 or more hours per week for 1-9 years and those who participated in cardiovascular exercise.
http://www.ncbi.nlm.nih.gov/pubmed/17012457
During early pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later miscarriage. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date of ovulation was 2.5.
After adjusting for confounders, the odds of preterm delivery were increased for women who climbed stairs >10 times per day (odds ratio = 1.60) and for women who engaged in purposive walking >4 days per week (odds ratio = 2.10). Leisure-time exercise (>60 days in the first and second trimesters combined) had a protective effect on preterm delivery (odds ratio = 0.51).
http://aje.oxfordjournals.org/content/147/7/628.full.pdf
We examined whether exercise during pregnancy is associated with chromosomally normal miscarriage. We hypothesized that associations would be confined to chromosomally normal losses since only these can be influenced appreciably by experiences during pregnancy. The study population comprises women with chromosomally normal and aberrant losses. Women who exercised during pregnancy had a lower risk of a chromosomally normal miscarriage (odds ratio 0.6). Other types of physical activity had little effect.
http://www.jstor.org/pss/3702185
Compared with women employed in sedentary jobs, a reduced risk of miscarriage was found for women working in jobs with either light (odds ratio = 0.18) or medium (odds ratio = 0.24) physical activity during the first pregnancy and over all pregnancies (light odds ratio = 0.32; medium odds ratio = 0.43). Analysis adjusting for BMI yielded similar results. Frequent crouching was associated with elevated risk of miscarriage (odds ratio = 1.82). Light activity was defined as... exerting up to 20 pounds of force occasionally, 10 pounds frequently, or a negligible amount constantly. Work involves walking or standing to a significant degree; or sitting most of the time while pushing or pulling arm or leg controls; or working at a production rate pace while constantly pushing or pulling materials. Medium activity was defined as... exerting 20-50 pounds of force occasionally, 10-25 pounds frequently, or up to 10 pounds constantly. Physical demand requirements are in excess of those for light work.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2863132/?tool=pubmed#R26
Sleeping < or =8 h/day (OR:3.80) was found to be a risk factor for first trimester miscarriage controlling for the effect of period of gestation. Sleeping < or =8 h/day (OR:2.04), standing < or =3 h/day (OR:1.83), exposure to cooking smoke (OR:3.83) and physical trauma during the pregnancy (OR:43.2) were found to be risk factors for second trimester miscarriage controlling for the effect of period of gestation. CONCLUSIONS: Sleep deprivation, a sedentary lifestyle, exposure to cooking smoke and physical trauma during pregnancy were risk factors for miscarriage. Most of the risk factors are therefore modifiable. Study does not clarify whether findings were controlled for nausea.
http://www.ncbi.nlm.nih.gov/pubmed
This study analyzed 436 patients undergoing intracytoplasmic sperm injection cycles. Patients answered a questionnaire and regression analysis examined the relationship between lifestyle and BMI with the intracytoplasmic sperm injection cycles outcomes. RESULTS: No influence of lifestyle and obesity was observed on the number of oocytes recovered. Obesity reduced the normal fertilization rate (coefficient: -16.0) and increased the risk of miscarriage (odds ratio: 14.3). Physical activity positively affected implantation (coefficient: 9.4), increased the chance of pregnancy (odds ratio: 1.83) and tended to decrease the risk of miscarriage (odds ratio: 0.30; p=0.068 not statistically significant). In addition, an inverse correlation was found between physical activity and BMI.
http://www.ncbi.nlm.nih.gov/pubmed/20597616
It is still not definitely resolved whether being physically active has any impact on the success of assisted reproduction treatment. To this end, this study used the International Physical Activity Questionnaire short form (IPAQ-sf). Data from the IPAQ-sf were classified into three categories: low, moderate and high physical activity as defined by the IPAQ working group. The subjects in the study were grouped according to their physical activity levels during treatment. None of the subjects met the criteria for high physical activity. The low activity group consisted of 68 women whereas moderate activity group consisted of 63 women. The study showed that women undergoing assisted reproduction treatment significantly decreased their activity level during the treatment period. However, women who were physically more active were more likely to have an increased implantation rate and a live birth.
http://www.ncbi.nlm.nih.gov/pubmed/20113966
Moderate physical activity during pregnancy does not contribute to low birth weight, premature birth or miscarriage and may actually reduce the risk of complications, according to a Michigan State University professor who contributed to the U.S. government's first-ever guidelines on physical activity. Specifically, the guidelines call for women to get at least 150 minutes of moderate-intensity aerobic activity per week during pregnancy and the postpartum period, preferably spread throughout the week.
http://www.sciencedaily.com/releases/2008/10/081008151322.htm
This study was designed to test the hypothesis that vigorous aerobic exercise during both the periconceptional period and early pregnancy increases the incidence of abnormal early pregnancy outcome. Exercise performance was prospectively monitored before and during pregnancy in 47 recreational runners, 40 aerobic dancers, and 28 physically active, fit controls. Pregnancy was diagnosed by an early test for beta-subunit human chorionic gonadotropin and viability was confirmed by ultrasonography at 40 days' conceptional age. Miscarriage occurred in 19% of the pregnancies. The incidence was 17% in the runners, 18% in the aerobic dancers, and 25% in the controls. We conclude that, in physically fit women, continuation of these types of aerobic activity at intensities between 50% and 85% of maximum during the periconceptional period and early pregnancy does not appreciably alter early pregnancy outcome.
http://www.ncbi.nlm.nih.gov/pubmed/2603898
Six hundred and three women aged 18–55 years whose most recent pregnancy had ended in first trimester miscarriage (<13 weeks of gestation; cases) and 6116 women aged 18–55 years whose most recent pregnancy had progressed beyond 12 weeks (controls) were questioned about socio-demographic, behavioral and other factors in their most recent pregnancy. There was no evidence of an association between early miscarriage and smoking in the first 12 weeks of pregnancy nor was there evidence of an effect of strenuous exercise. (There was an increase in miscarriages in those who exercised >4 times per week (odds ratio = 1.31) but this was not statistically significant)
http://onlinelibrary.wiley.com/doi/10.1111/j.1471-0528.2006.01193.x/pdf
Female mice were arbitrarily assigned to a heavily exercised group, a moderately exercised group, or a sedentary group. Exercised groups were subjected to a progressive treadmill training routine, 6 days a week (60 min per day) for a total of 9 wk. Following mating after 6 wk of training, treatment groups continued to exercise at preconceptual intensities. The numbers of implants, miscarriages, live fetuses, mean fetal weight, and developmental stage were unaffected by the exercise treatment. A detailed fetal examination revealed no significant skeletal or gross tissue abnormalities in any of the experimental groups.
http://www.ncbi.nlm.nih.gov/pubmed/2888217
Among women who were in paid employment, there was no evidence of an effect of sitting or standing for more than 6 hours/day or of lifting heavy objects or people on the risk of first trimester miscarriage.
http://onlinelibrary.wiley.com/doi/10.1111/j.1471-0528.2006.01193.x/full