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Dietary sodium restriction is used in the Netherlands in the prophylaxis of preeclampsia. To study the effects of long-term sodium restriction on the intake of other nutrients and the outcome of pregnancy, 68 healthy nulliparous pregnant women were randomly assigned to either a low-sodium diet (20 mmol/24 h) or an unrestricted diet. The diet was consumed between week 14 of gestation and delivery. The dietary intakes of energy, fat, protein, carbohydrate, sodium, potassium, and calcium were estimated with the dietary-history technique. A low-sodium diet reduced the intake of protein (by approximately 15 g/24 h), fat (by 20 g/24 h), and calcium (by 350 mg/24 h) and tended to decrease the energy intake (by approximately 0.7 MJ/24 h). The intakes of carbohydrate and potassium did not differ between the groups. The maternal weight gain was less in the low-sodium group (6.0 +/- 3.7 compared with 11.7 +/- 4.7 kg). Mean birth weight was not significantly different (3.2 +/- 0.5 compared with 3.4 +/- 0.5 kg).

In 19 normal pregnancies between 37 and 39 weeks of gestation, the blood flow velocity waveform (FVW) of the umbilical artery was studied in relation to fetal breathing movements, fetal heart rate (FHR) and the fetal heart rate patterns (FHRPs) A and B. FHRP A is stable, with a narrow oscillation bandwidth, FHRP B shows a wider oscillation bandwidth. Although for state-assessment it is necessary to record three variables simultaneously, the linkage of these variables in the near-term healthy fetus is such, that FHRP A and B may be used for the assignment of behavioural states 1F and 2F. The FVW was characterized by the Pulsatility-Index (PI). Presence of fetal breathing movements strongly disturbed the regularity of the FVW. A significant inverse relationship between FHR and PI was established. A weighted regression coefficient was calculated: PI decreases 0.0075 with an increase of FHR of 1 beat per minute (PI140 = PI / 0.0075(FHR - 140]. The PI was higher during periods of FHRP A as compared to FHRP B. However, this difference disappeared, when the influence of FHR was taken into account by normalising all PIs to a standard heart rate level of 140 bpm. One should perform the umbilical artery blood flow measurements in absence of fetal breathing--(causing irregularity of the FVW) and body movements (because of accompanying FHR accelerations) and FHR should be taken into account when evaluating the FVWs.

Uterine artery blood flow velocity waveforms (FVW) were recorded longitudinally in normal pregnancies (n = 41) at 4-week intervals from a gestational age of 18 weeks onwards. Furthermore, reproducibility of the uterine artery FVWs and the relation with maternal heart rate (MHR) was studied. The uterine artery FVW showed a low resistance flow pattern already from 18 weeks onwards, with high diastolic flow velocity relative to systolic flow velocity. Mean values (+/- S.D.) for the Pulsatility-Index (PI) before and after 32 weeks of normal pregnancy were 0.73 (+/- 0.17) and 0.67 (+/- 0.15) respectively; for the A/B ratio these values were 1.98 (+/- 0.30) and 1.85 (+/- 0.25) respectively. Intra- and interobserver reproducibility could be established for uterine artery FVW analysis. A varying time-period between the FVWs (0-4 min), repositioning of the flow probe and different observers did not cause any systematic effect on the PI, although variation increased in case of a longer time-period between the FVWs. Overall variation of the PI in the reproducibility experiments appeared to be caused more by inter- than intrapatient variance. Inter- and intrapatient variance were in the same range for the results of the longitudinal study. A statistically significant, inverse relationship between uterine artery PI and MHR could be established in a majority of cases. The mean regression coefficient for all patients of the reproducibility study was -0.0061; PI decreases with 0.0061 when maternal heart rate increases 1 beats/min.

Uterine artery blood flow velocity waveforms (FVW) were recorded longitudinally in 41 women with undisturbed pregnancy as well as in 32 women with complicated pregnancy at 4-week intervals from a gestational age of 18 weeks onwards. Of these women, four did not complete the study. In a second group of 76 patients at least one FVW was recorded after admission to the obstetrical department because of complicated pregnancy. The Pulsatility-Index (PI) for normal pregnancy was based on the results of the 41 women with undisturbed pregnancy (Mulders et al. (1988) Early Hum. Dev., 17, 55-70). The complete study group (n = 145) was divided in two groups, based on the value of the last measured uterine artery PI before delivery in the abnormal PI group (PI greater than or equal to 1.02 before 32 weeks or PI greater than or equal to 0.91 after 32 weeks, n = 38) hypertension, fetal distress during pregnancy, premature delivery, small for gestational age babies (SGA) and lower placental weight were all significantly increased. In each of the groups of patients with either SGA, fetal distress during pregnancy, pre-existing hypertension with proteinuria and pregnancy-induced hypertension with or without proteinuria the mean PI was significantly increased as compared to the results in normal pregnancy. Sensitivity and specificity of the last uterine artery PI for the detection of SGA and/or fetal distress during pregnancy were 48.8% and 82.7%, respectively. The longitudinally studied women (n = 73) were divided in two groups, based on uterine artery PI before 32 weeks of gestation; in the abnormal PI group (PI greater than or equal to 1.02, n = 12) pregnancy was more complicated by premature delivery and low birth weight. Sensitivity for the early prediction of pathological pregnancies (at least one pathological phenomenon as mentioned above) was 30.4%, whereas specificity was 90.0%.