Our estimate of miscarriage rate could be an underestimate as many miscarriages go unnoticed early in pregnancy.
To do this, the number of terminations is weighted by the estimated risk of miscarriage, allowing for the fall in risk with increasing gestational maturity and the increase in risk with increasing maternal age.
27 We estimated the HR of miscarriage according to weekly amount of exercise performed during pregnancy and according to the type of exercise most often performed, using nonexercisers as the reference.
We have presented odds ratios estimating the risk of miscarriage with (Model III) and without (Model II) controlling for risk behaviours related to use of alcohol, tobacco and illegal drugs because the degree to which these behaviours lie on the causal pathway is unknown and controversial.
Nineteen outbreaks were identified from historical records (4, 7 – 20 ), and of these, 16 allowed estimates to be made of case fatality, and 15 allowed estimates of the proportion of miscarriage or premature birth.
Compared with the results of a population-based study in India, 28 our estimates of induced abortions, miscarriages, and stillbirths are slightly higher than those found in India; that study found that 1.7% of all pregnancies resulted in induced abortions, 4.9% in miscarriages, and 2.1% in stillbirths.
The estimated positive predictive value of miscarriage diagnoses recorded in the DNRP is 97%.
The pooled estimate for the outcome of miscarriage was 3.23 (95% CI, 1.64 to 6.36), and for the outcome of perinatal mortality an odds ratio of 3.03 (95% CI, 1.87 to 4.92),.
To avoid the use of overlapping data from the Costa Rica HPV Trial, we estimated the relative risk of miscarriage less than 90 days from bivalent HPV vaccination and overall for exposed and unexposed pregnancies, using data accrued after the original report.
