| 1. |
- Englund-Ögge, Linda, et al.
(författare)
-
Maternal characteristics and pregnancy outcomes in the NICE birth cohort: an assessment of self-selection bias
- 2022
-
Ingår i: Journal of Maternal-Fetal and Neonatal Medicine. - : Informa UK Limited. - 1476-7058 .- 1476-4954. ; 35:25, s. 9014-9022
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Prospective birth cohorts are essential for identifying associations between exposures and outcomes. However, voluntary participation introduces a potential bias due to self selection since the persons that chose to participate may differ in background characteristics and behaviors. Objectives: To investigate potential bias due to self-selection in the Nutritional impact onImmunological maturation duringChildhood in relation to theEnvironment (NICE) birth cohort in northern Sweden. Methods: Women in the NICE birth cohort (N = 621) were compared to nonparticipating pregnant women in Norrbotten County in northern Sweden who were eligible for participation (N = 4976) regarding maternal characteristics and lifestyle. Maternal characteristics and pregnancy outcomes were compared between the groups and associations between exposures (smoking, folic acid, BMI, parity, education) and pregnancy outcomes (birth weight and gestational age) were analyzed by linear regression analyses, examining any interaction with the group. Results: NICE participants were more highly educated, older and more likely to cohabit than the non-participants. They more often took folic acid and multivitamin supplements and less often smoked during early pregnancy. Pregnancy outcomes (mode of delivery, gestational age at delivery, birth weight and APGAR score) did, however, not differ significantly between participants and non-participants. Smoking, BMI, education and parity affected gestational age and birth weight, but the associations were of similar magnitude in participants and non-participants, with no significant effect on the group. Conclusion: Self-selection to the NICE study was evident in some factors related to lifestyle and socioeconomic characteristics but did not appear to skew pregnancy outcomes or alter well-known effects of certain lifestyle parameters on pregnancy outcomes.
|
|
| 2. |
- Flatley, Christopher, et al.
(författare)
-
Placental weight centiles adjusted for age, parity and fetal sex
- 2022
-
Ingår i: Placenta. - : Elsevier BV. - 1532-3102 .- 0143-4004. ; 117, s. 87-94
-
Tidskriftsartikel (refereegranskat)abstract
- The weight of the placenta can be indicative of efficacy in nutrient and oxygen supply. Furthermore, it has been suggested that a measure of the placenta's ability to adequately supply nutrients to the fetus can be found in the relationship between birth weight and placental weight expressed as a ratio. Our aim was to develop age adjusted placenta weight and birth weight to placenta weight ratio reference curves that are stratified by maternal parity and fetal sex.We included singleton, non-anomalous births with a gestational age inclusive of 28+0 weeks to 42+6 weeks. Excluded were pregnancies of multiplicity, fetuses with congenital abnormalities, stillbirths and pregnancies that had placental complications (ie placenta previa or abruption). Generalised additive model for location, shape and scale (GAMLSS) was used to fit reference curves.We stratified 97,882 pregnancies by maternal nulliparity status and fetal sex. Extensive assessment model goodness-of-fit showed appropriate modeling and accurate fit to the four parameters of distribution. Our results show accurate model fit of the reference curves to the data. We demonstrated that the influence that parity has on the placenta weight is far greater than that exerted by fetal sex, and that the difference is dependent on gestational age.This is the largest presentation of age and parity adjusted placenta weight and feto-placental weight ratio reference ranges to date. The difference observed between nulliparous and multiparous pregnancies could be explained by biological memory and the remnants of maternal endo-myometrial vascularity after the first pregnancy.
|
|
