Influences on the fetal heart rate in mid-pregnancy and the relationship between fetal heart rate and size at delivery

Haemoglobin and ferritin levels were measured in early pregnancy and at 28 weeks. At eighteen weeks the fetal heart rate was recorded using Doppler ultrasound, the fetus was measured and placental volume was estimated by a parallel planimetric technique. The fetus was again measured at twenty-eight weeks and, at delivery, baby and placenta were weighted and anthropometric measurements of the baby were made.

442 women were entered into the study, including 216 who were nulliparous. In early pregnancy, 5% had haemoglobin ≤ 11g/dl and 21.3% had ferritin ≤ 12μg/l.

Fetal heart rate in mid-pregnancy was negatively associated with duration of gestation (r = 0.13, p=0.009). No changes were linked with haemoglobin or ferritin levels, or with estimated fetal weight or placental volume in mid-pregnancy. There was no difference in fetal heart rate between smokers and non-smokers, nor was there any association with maternal height or weight. Estimated fetal weight and placental volume were positively correlated with gestation, but there was no correlation with maternal haemoglobin or ferritin.

Fetal heart rate in mid-pregnancy was not related to fetal, placental or neonatal size. At delivery, placentae were larger in parous women and those who weighted more at booking and had lower late pregnancy haemoglobin. Birth weight was greater in parous, tall women and those who had low haemoglobin in late pregnancy. Gestation of delivery was found to be significantly associated with fetal heart rate in mid-pregnancy and strongly associated with fetal dimensions in mid-pregnancy.

These findings do not support the hypothesis that maternal haemoglobin levels are implicated in the setting of fetal heart rate by mid-pregnancy. Although maternal haemoglobin levels may result in placental adaptation, possibly to compensate for decreased oxygen supply, no fetal adaptation has been shown.

University of Southampton

Grant, Simon Richard

1998

Grant, Simon Richard

Grant, Simon Richard (1998) Influences on the fetal heart rate in mid-pregnancy and the relationship between fetal heart rate and size at delivery. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

442 women were entered into the study, including 216 who were nulliparous. In early pregnancy, 5% had haemoglobin ≤ 11g/dl and 21.3% had ferritin ≤ 12μg/l.

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