Summary. Serum iron, serum iron‐binding capacity, serum ferritin and erythrocyte protoporphyrin were determined during uncomplicated pregnancy in 45 healthy women; 22 were given oral iron while the others were given a placebo. When iron was not given, 15 out of 23 women had exhausted iron stores and iron deficiency at term, as judged from low serum ferritin, low serum transferrin saturation and high erythrocyte protoporphyrin values. Only seven of them had a haemoglobin concentration between 10 and 11 g/dl at term but none had values < 10 g/dl. In the iron‐treated group (n=22) none of the women developed iron deficiency. Serum ferritin was the most sensitive and specific test of iron deficiency. A practical procedure to detect iron deficiency and to control iron supplementation in pregnancy is suggested.

Maternal serum urate levels were studied in 50 normal pregnancies and 72 cases of severe pre-eclampsia. Markedly elevated levels of serum urate were found in severe pre-eclampsia, compared with normal pregnancy. In severe pre-eclampsia significantly higher levels were found prior to parturition in cases of growth retardation and perinatal distress, compared with patients whose newborns were of normal size and condition. Particularly high serum urate levels were found early in the third trimester in cases of perinatal death. A slight but significant correlation was found between the weight centile of the newborn and the last maternal urate level before parturition. A rapidly rising urate level reliably predicted perinatal distress. The last maternal serum urate before parturition was correlated with the hemoglobin and erythrocyte volume fraction values in the same blood sample.

The Hb level during pregnancy was followed in 113 non-anaemic women with uncomplicated pregnancy and birth weight of the baby above the 2.5th percentile. There was an inverse correlation close to statistical significance between the birth weight of the baby and the lowest Hb level reached during pregnancy as well as the Hb level in late pregnancy (38th week). A group of seven non-anaemic women with birth weight of the baby below the 2.5th percentile had a significantly higher (p less than 0.001) Hb level in late pregnancy than the normal group. Four of these cases had a statistically significant higher Hb level already in the second trimester. Trends in the reproductive history, complaints in the present pregnancy as well as results of hormone assays and the condition of the baby indicated that the seven cases represented a pathological group with fetal growth retardation. None of the women in the two groups were treated with diuretics. All had iron supplementation in high doses.

In a series of 24 apparently uncomplicated pregnancies with small-for-dates newborn at or below the tenth percentile, 15 women had hemoglobin (Hb) levels 2 SD above the mean value of normal distribution in late pregnancy. Among these 15 was the only case with intrauterine death of unknown cause. In a series of 15 cases intrauterine fetal death of unknown cause, before start of labor 10 had Hb levels 2 SD above the mean, while in a series of 16 cases of late abortion where the fetus was alive until labor started, only one had a Hb level 2 SD above the mean. In three cases with serial Hb estimations, the levels were 2 SD above the mean one week or more before intrauterine fetal death. Two of these cases also had been observed during a successful pregnancy in which the Hb levels were within normal limits. It is concluded that high Hb levels during pregnancy may indicate a fetus at risk. High viscosity of the mother's blood may impede the uteroplacental circulation, casing placental infarction, growth retardation and ultimately fetal death.

Maternal Hb levels during the third trimester were studied in relation to certain maternal and fetal parameters in 877 apparently normal pregnancies. Low Hb levels at term were closely associated with increased frequency of newborns in the heavy weight-for-date group. Conversely, high maternal Hb levels were closely associated with an increased frequency of newborns in the light weight-for-date group. The maternal Hb levels both in the early third trimester and at term were significantly higher in mothers of small-for-date newborns than in those with newborns of normal weight. In both groups the maternal Hb levels increased significantly during the third trimester of pregnancy. High maternal Hb levels both early and late in the third trimester of pregnancy should be a matter of concern rather than of reassurance.