Correlation analysis of Each Variable of Fetal Heart rate in Pregnancy induced hypertension and Intrauterine fetal growth restriction

Yoon, Sang Soon; Kim, Seong Hee; Joo, Myung Hee; Chung, Kyung Mee; Hwang, Jeong Hyae; Chung, Sung Ro; Moon, Hyung; Cha, Kyung Joon; Park, Young Sun; Park, Moon Il

Abstract

OBJECTIVE
We aim to analyze each variable of FHR in high risk pregnancies, namely intrauterine growth restriction (IUGR) and pregnancy-induced hypertension (PIH) including chronic hypertensive vascular disease (CHVD), mild and severe preeclampsia to build an objective decision basis using correlation analysis.
METHODS
The patients were divided into two groups (500 normal pregnancies and 500 high risk pregnancies related to IUGR, CHVD, mild and severe preeclampsia), and then subdivided into intrauterine pregnancy before 24 weeks, 25-39 weeks, and after 40 weeks. We compared the canonical correlation between each group using variables of FHR after nonstress test (NST).
RESULTS
In high risk pregnancies, the linearity was 0.6-0.8 in intrauterine pregnancy before 24 weeks, 0.53-0.68 in 25-29 weeks, 0.50-0.60 in 30-34 weeks, 0.38-0.45 in 35-39 weeks and 0.42-0.55 in after 40 weeks. In normal pregnancies, the linearity was 0.44-0.52 in intrauterine pregnancy before 24 weeks, 0.38-0.45 in 25- 39 weeks which was stable, and there was no specific change in after 40 weeks. Before 32 weeks, canonical variates of FHR_D and FHR_I revealed highest (0.36, 0.47 respectively) in high risk pregnancy and fetal movement and signal loss was the most valuable factors in normal pregnancy. In between 33 to 37 weeks, fetal movement (0.40) and signal loss (0.48) were related most closely in high risk pregnancies and 0.34 and 0.49 respectively in normal pregnancies which show similar pattern. In contrast, FHR_D was most highly related to the duration of pregnancy and FHR_I to fetal movement (0.38) in high risk pregnancy. In normal pregnancies, fetal movement (0.40) and signal loss (0.52) showed the highest linearity.
CONCLUSION
The pregnancy with intrauterine growth restriction and pregnancy induced hypertension has more linear relation and less complexity in each variable of FHR than the normal pregnancy group. The formal, functional underdevelopment of fetus may results in the increasement of the linear depedent relation in each variable of FHR in these type of high risk pregnancies.