Date of Award

2007

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

First Advisor

Errol Norwitz, M.D., Ph.D.

Abstract

This retrospective case-control study was designed to investigate the relationship between placental localization and intrauterine growth restriction (IUGR). Pregnant women with an anatomic survey from January 1, 2000, to December 31, 2005, and delivery of the pregnancy at Yale-New Haven Hospital (YNHH) were identified using clinical and billing records. Multiple gestation, fetal anomaly, and incomplete medical information were reasons for exclusion. Cases (N=69) were consecutive pregnancies with evidence of IUGR (estimated fetal weight <10th percentile for gestational>age) at last follow-up ultrasound. Randomly selected controls (N=258) from the same time period had no evidence of IUGR. Maternal, ultrasound, delivery, and perinatal data were collected by retrospective medical record review, and IUGR cases and non-IUGR controls were compared using the Students t-test, Wilcoxon test, Chi-square analysis, Fishers exact test, and ANOVA. Placental location was determined from the anatomic survey record (obtained at 18.4 ± 1.2 weeks gestation in the IUGR group and 18.2 ± 1.0 weeks gestation in the control group; P=0.18). Multivariate logistic regression with adjustment for confounders was used to investigate the association between IUGR and placental localization. Consistent with known predictors of IUGR, the IUGR group had a higher proportion of black women (36.4% vs. 19.8%, P=0.03), chronic hypertension (26.0% vs. 3.5%, P<0.001), and hypertensive disorders of pregnancy (36.2% vs. 5.0%, P<0.001). Mean birth weights of IUGR and non-IUGR pregnancies differed by 2 kilograms (3244 ± 625 grams vs. 1277 ± 637 grams, P<0.001). IUGR infants were more likely to receive antenatal steroids, deliver preterm, deliver by cesarean section, and be admitted to neonatal intensive care. In both IUGR and non-IUGR pregnancies, the placenta was most commonly anterior or posterior. Unilateral placentas were three times more common in the IUGR group than in the non-IUGR group (17.4% vs. 5.0%, P=0.01). IUGR pregnancies were over four times as likely as control subjects to have unilaterally-located placentas compared to anterior placentas (OR 4.8, 95% confidence interval, 1.9-11.7). Adjusting for ethnicity, chronic hypertension, and hypertensive disorders of pregnancy did not affect this finding (OR 4.6, 95% confidence interval 1.6-13.5). In conclusion, we compared a group of 69 IUGR pregnancies to 258 non-IUGR controls and found intrauterine growth restriction to be associated with unilateral placentation.

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