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Biomedical subjects

Mark P Umstad

Publications and source records attributed to Mark P Umstad.

3 recordsLinked to original sources

Maternal dietary intake in twin pregnancies: does it diminish towards term?

We tested the hypothesis that energy intake among women with twin pregnancies decreases in late gestation, as the uterus enlarges and they become increasingly uncomfortable. We asked women to recall dietary intake for the previous 24 hours, every 2 weeks from around 29 weeks of gestation, using a photographic atlas and other strategies to estimate portion size. Eighty women provided data at around 29, 31, 33 and 35 weeks of gestation. We calculated total energy intake, and energy intake from carbohydrate, fat and protein. Data were log transformed to reduce skewness. Using mixed effects linear regression models, we found minimal evidence that total energy intake changed over this time period, either before or after adjustment for potential confounding factors (95% confidence interval for relative change per week: -1.4%, 0.6%). There was weak evidence of a small decline in carbohydrate intake over time, both before and after controlling for energy intake. We cannot exclude change in energy intake or diet composition before 29 weeks or after 35 weeks of twin gestation.

Diet↗

Association between erythropoietin in cord blood of twins and size at birth: does it relate to gestational factors or to factors during labor or delivery?

We hypothesized that cord blood erythropoietin (EPO), a marker of fetal hypoxia, relates to gestational factors and not solely those associated with delivery. We investigated the association between birth weight SD score (SDS) and cord blood EPO in 290 twins (145 pairs), assessing the influence of gestational versus perinatal factors by comparing the association in those who were delivered by elective cesarean (CS) with that in other delivery modes. Blood EPO values were skewed, so geometric means are presented and log EPO values were used in statistical models. The birth size-EPO association was estimated in mixed-effects models that included terms that represented difference in log EPO and mean log EPO for each twin pair. Within-pair estimates of the association were unconfounded by maternal factors (because these were perfectly controlled). Geometric mean EPO was higher in boys versus girls (24.4 versus 17.0 IU/L; p = 0.0001) and increased with gestational age (p = 0.0003) but was similar after elective CS versus other delivery modes. The negative birth size-EPO association was stronger in infants who were delivered by elective CS than by other delivery modes [beta for log(2) EPO: -0.56 (95% CI, -0.77 to -0.36) versus -0.27 (-0.42 to -0.12), respectively; p = 0.02 for interaction). Because the association was seen after elective CS delivery, cord blood EPO must relate to factors during gestation, not just perinatal factors. There was no evidence of an association between birth weight SDS and pair mean log EPO, indicating that the association is entirely due to fetus-specific rather than pair-specific factors.

Cesarean Section↗