We estimate Cox proportional hazard models for parity progression based on the presence of kin and non-kin in the household while controlling for a large number of individual and community-level characteristics.
We decided a priori to adjust all models for parity (nulliparous, parous, or missing data), smoking status (current, never, previous, missing data) and body mass index (BMI) in kg/m (continuous scale), due to modest variation in prolactin levels over these factors in healthy women [ 10].
Thus, adjusting the model for parity could have improved the correlation between dietary cadmium intake and the biomarkers.
Table 3 shows the estimates of the same models for later parity cows (parity 2 and 3).
Finally, we ran separate models adjusted for parity in sensitivity analyses, given the uncertain causal relationship between parity, POPs, and TTP.
Hence, refined models adjusting for parity, education, smoking, delivery mode, folic acid use, and preterm birth were used to examine potential effects of a priori defined race/ethnicity and infant sex, and analyses were conducted among three racial/ethnic groups (Blacks, Whites and Hispanics) as well as by sex of the offspring.
Recent studies signify a dramatic advance in our understanding of this phenomenon, and indicate a 'cell fate' model for parity-related changes that lead to protection against breast cancer.
‡Adjusted matched model accounted for parity, socioeconomic status, birth year, and maternal age.
†Adjusted unmatched model accounted for parity, socioeconomic status, birth year, maternal age, ethnicity, and previous birth outcome.
Nevertheless, despite the model controlling for parity and many other known confounders, there remains a greatly elevated risk of PPH for women who have planned hospital births in comparison to those who plan a home birth (odds ratio, 2.5, 95% confidence interval, 1.7 to 3.8).
This is not a purely theoretical concern; as an illustration, in our study most elemental components were statistically significantly associated with birth weight in crude models and in models without adjustment for parity, but not in the most comprehensive models we used, which included parity.
