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The prediction of pregnancy outcome by haemoglobin measurement before 20 weeks' gestation
K Harding1, S Evans, J P Newnham
1Women's and Infant's Health Research Foundation, University Department of Obstetrics and Gynaecology at King Edward Memorial Hospital for Women, Subiaco, Western Australia.
Maternal haemoglobin levels were measured before 21 weeks' gestation in a prospective study of 1276 singleton pregnancies. Reference ranges were constructed and then applied to a further cohort of 1227 singleton pregnancies to determine the ability of haemoglobin level before 21 weeks' gestation to predict pregnancy outcome. Haemoglobin level decreased significantly with advancing gestational age from 6 to 21 weeks (P < 0.05). Low haemoglobin level was associated with a decreased risk of pregnancy-induced hypertension (adjusted odds ratio 0.51, 95% CI 0.35-0.74). High haemoglobin level was positively correlated with subsequent pregnancy-induced hypertension (P = 0.002) with values > 95th percentile for gestational age having positive and negative predictive values of 33% and 94% respectively. Haemoglobin values (either high or low) were not predictive of proteinuric pre-eclampsia, preterm prelabour rupture of the membranes, preterm birth, low birth weight or the need for neonatal resuscitation of admission to the special care baby unit. The finding of a high maternal haemoglobin before 21 weeks' gestation is not sufficiently predictive of pregnancyinduced hypertension to be of clinical use, but the ability of a low level to predict favourable outcome may be of use in a scoring system designed to identify women suitable for midwifery-based care.
Maternal haemoglobin levels were measured before 21 weeks' gestation in a prospective study of 1276 singleton pregnancies. Reference ranges were constructed and then applied to a further cohort of 1227 singleton pregnancies to determine the ability of haemoglobin level before 21 weeks' gestation to predict pregnancy outcome. Haemoglobin level decreased significantly with advancing gestational age from 6 to 21 weeks (P < 0.05). Low haemoglobin level was associated with a decreased risk of pregnancy-induced hypertension (adjusted odds ratio 0.51, 95% CI 0.35-0.74). High haemoglobin level was positively correlated with subsequent pregnancy-induced hypertension (P = 0.002) with values > 95th percentile for gestational age having positive and negative predictive values of 33% and 94% respectively. Haemoglobin values (either high or low) were not predictive of proteinuric pre-eclampsia, preterm prelabour rupture of the membranes, preterm birth, low birth weight or the need for neonatal resuscitation of admission to the special care baby unit. The finding of a high maternal haemoglobin before 21 weeks' gestation is not sufficiently predictive of pregnancyinduced hypertension to be of clinical use, but the ability of a low level to predict favourable outcome may be of use in a scoring system designed to identify women suitable for midwifery-based care.