Furthermore, they were asked about daily smoking habits (type, amount, duration) and changes in habits during pregnancy (quit smoking (gestational week), reduced smoking (gestational week), occasional smoking) and use of substitutes in form of nicotine patches, spray or chewing gum (duration, trimester) and exposure to passive smoking (daily extent).
Based on fetal biparietal diameter (BPD) in the second trimester, pregnancy duration is calculated to be somewhat shorter (mean 280.6 days) [ 3] than previously thought.
Sleep duration decreased in the third trimester compared with before pregnancy, dropping from a mean of 8.1 hours to 7.5 hours a night.
These analyses included stratification of results according to maternal age, BMI, trimester of pregnancy, duration of hospital stay, and calendar year (before and after 2004 based on the publication of first national guideline for thromboprophylaxis during pregnancy).
We obtained information on socioeconomic background, maternal diseases, obstetric history, parity, child's sex, fetal exposure to alcohol (ever exposure during pregnancy), prenatal cigarette smoking (at least one cigarette a day during the last trimester), type and duration of breast-feeding, education, and social class through questionnaires administered in person after delivery and at 48 months.
Most admissions were of short duration and occurred during the third trimester.
For whole pregnancy, the best fitting fractional polynomial model was β1 x - 2+ β2 x-0.5, and for the first, second and third trimesters, the best fitting functional forms were x - 1, ln(x) and x-0.5, respectively, where x denotes weekly average black smoke averaged over the entire duration of pregnancy or the corresponding trimester.
Therefore, because of temporal variation in pollutant levels, the shorter duration of exposure during the third trimester among women with preeclampsia could have resulted in biased exposure assessment (Lewis et al. 2011; O'Neill et al. 2003).
When the duration of a prescription overlapped between trimesters, women were defined as exposed in both time periods.
The prevalence of microalbuminuria in the first trimester was 10%, median diabetes duration was 11 years, and third-trimester A1C was 6.6%.
The aim of the present study was therefore to assess the effect of second trimester fetal size on the duration of pregnancy and the influence of ultrasound dating.
