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Originally Posted by seafox  I figure Ill slow down when I need to, but I did have a m/c this past summer, so now I am a bit concerned. What is the connection between exercise and m/c? My doc had told me as long as it wasn't a big shift from what I was doing before I should be fine.
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*envy* I used to play Ultimate, before I left Seattle. A strong community is much harder to find in the burbs on the East Coast, and in the hinterlands of the UK, fergit it.
There is one study out of Denmark. I've bolded the most important sentence in the abstract. You can get the study for free from PubMed if you'd like to read the paper yourself. I'm not that impressed by it, and plan to keep exercising.
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BJOG. 2007 Nov;114(11):1419-26. Epub 2007 Sep 17.
Leisure time physical exercise during pregnancy and the risk of miscarriage: a study within the Danish National Birth Cohort.
Madsen M, Jørgensen T, Jensen ML, Juhl M, Olsen J, Andersen PK, Nybo Andersen AM.
Department of Child Health, National Institute of Public Health, Copenhagen K, Denmark.
OBJECTIVE: To examine the association between leisure time physical exercise during pregnancy and the risk of miscarriage. DESIGN: Prospective study with elements of retrospective data collection. SETTING: Denmark 1996-2002. POPULATION: A total of 92,671 pregnant women enrolled in the Danish National Birth Cohort and interviewed subsequently. METHODS: Data on exercise during pregnancy and potential confounders were obtained through computer-assisted telephone interviews either during pregnancy or after an early miscarriage. Outcome of pregnancy was identified by register linkage. Using Cox regression analysis, we estimated the hazard ratio (HR) of miscarriage according to weekly amount of exercise and the type of exercise. The HR was estimated for <11, 11-14, 15-18, and 19-22 weeks of gestation, respectively. MAIN OUTCOME MEASURES: Miscarriage, defined as fetal loss before 22 completed weeks of gestation. RESULTS: A stepwise increasing relation was found between amount of exercise and risk of miscarriage, where risk of miscarriage increased by amount of exercise up to HR = 3.7 (95% CI 2.9-4.7) for women who exercised more than 7 hours per week compared with nonexercisers. 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. CONCLUSIONS: This study suggests that exercise early in pregnancy is associated with an increased risk of miscarriage. The results should, however, be interpreted cautiously as potential bias arising from retrospective data collection may explain part of the association. |
If you look at the actual numbers in the study, out of 23,599 women enrolled in the prospective part of the study between 0-11 weeks of pregnancy, the odds ratio for a m/c for non-exercisers was set at 1. The highest increase in risk was for those exercising 270-419 minutes (4.5 hrs - 7 hrs) per week. That increased the risk to 1.7.
They only do the high-impact calculations for combined prospective and retrospective data. In that case, out of women who performed high-impact exercise for 75-269 minutes/week (some unknown number out of 38,489), 49 had a miscarriage. That is a supposed hazard ratio of 3.6, if you call the number of miscarriages among non-exercisers 1. Bah, I say.
So, you set a number at 1 for ease of statistical analysis. Your total number is 38489. Total number of miscarriages in that number is 621. What is your percent chance of having a miscarriage? 621/38489 or 1.6%. According to their data (retrospective and prospective), high impact exercise would increase your risk to 1.6% x 3.7 = 5.92%
The risk with using retrospective data is that people remembering traumatic events, such as miscarriages, are primed by questions like the ones asked in the study. They realize quickly that the study is trying to figure out why they miscarried, the study interviewers ask about exercise, and bingo, they are adding minutes to their exercise time, or increasing the intensity of their exercise. People don't mean to do this--it just happens.
An important sentence from the paper: "Risk estimates based only on the prospective data material were not as large as in the total data material and hardly any statistically significant results emerged." !!! Ah, so the best data don't make an interesting publication? Well, then!
My take on this (IANAMD, but I am a scientist and a vet)--if you're really worried about m/c because of lots of prior losses, maternal age, or some other reason, give up running and take up swimming or bike riding. Otherwise, I wouldn't worry about it.
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) and so am really tired. But, I had a nap and now it's midnight and I'm wide awake! 
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Today it all sort of came to a head.
I have so had these crazy days... it's difficult not to feel like a bad mama, but you are doing the best you can. I'm sure you give your dd loads of love and patience, but it gets to the point where it's just too much sometimes. It's also doubly difficult in early pregnancy. You will get through it though, and try not to beat yourself up! Give your dd a little kiss while she's sleeping like an angel tonight, feel her soft little cheek, and try and breathe in some renewed energy and strength for the day to come. 
Sending you loads of good vibes! 
