Circadian changes and sex-related differences in fetal heart rate parameters.

BACKGROUND: Previous researchers have studied circadian changes in the fetal heart rate (FHR) on small sample sizes and in a strictly controlled environment. This study was undertaken to investigate these changes during the late second and third trimesters, using a portable fetal electrocardiogram recording device (Monica AN24) in pregnant women in home and hospital environments with unrestricted mobility. METHODS: This was a prospective cohort study of 54 pregnant women with uncomplicated singleton pregnancies between 25 and 40 weeks gestation. FHR recordings were made up to 16 h at home or in the hospital setting in the United Kingdom. FHR data over 90 min periods were averaged and the day (7:00 am-11:00 pm) and night (11:00 pm-7:00 am) data from the same individual were compared. Data were examined for evidence of sex-related differences. RESULTS: During the night, there was a significant reduction in basal heart rate (bFHR) and a significant increase in short term variation (STV) and long term variation (LTV) (P < 0.05). Basal FHR decreased (P < 0.002), whereas LTV increased (P = 0.014) with advancing gestation. Male fetuses showed greater day: night variation than females regardless of gestation (P = 0.014). There was a higher bFHR in fetuses monitored during the day in hospital (P = 0.04). CONCLUSION: This study demonstrates that there are sex-, environment and time-related differences in the FHR parameters measured. These differences may need to be considered taken when interpreting FHR data.

Smoking in pregnancy affects the fetal heart: possible links to future cardiovascular disease.

OBJECTIVES: To investigate effects of maternal smoking on the fetal heart rate (FHR) in ambulatory patients using a portable fetal electrocardiogram recording device. METHODS: A prospective cohort study of 43 pregnant smokers and 43 non-smoking gestation-matched controls with uncomplicated singleton pregnancies. Smokers were divided into light (1-10) and moderate (11-20 cigarettes/d). The FHR was recorded for 16 h with smokers smoking at will, using an event button to record when they lit a cigarette. Fifty recordings were made in the patients' homes with 36 in ambulatory inpatients. Three consecutive 30-min epochs (before, during and after smoking) were compared with the controls. RESULTS: Basal FHR was significantly lower before smoking in the foetuses of smokers compared with non-smokers (p = 0.048). During smoking, there was a significant dose-dependent fall in short-, long-term and true beat-to-beat variabilities (p = 0.004, p < 0.0001 and p = 0.024, respectively). CONCLUSION: Maternal smoking leads to reversible changes in FHR variability that mimic those associated with an increased incidence of adverse cardiovascular events in adults. As heart rate and variability reflect the autonomic control of the heart, our findings suggest that maternal smoking interferes with the autonomic control of the FHR.

Fetal pulmonary valvuloplasty for critical pulmonary stenosis or atresia with intact septum.

Progressive stenosis of the semilunar valves in utero can be life threatening. We treated two fetuses with complete or almost complete pulmonary atresia and imminent hydrops (increased cardiothoracic ratio, pericardial effusion, holosystolic tricuspid regurgitation extending into diastole, and abnormal venous Dopplers). We dilated the pulmonary valve of two fetuses in utero at 28 and 30 weeks' gestation, through the mothers' abdomens. After the procedure, the fetuses had decreased signs of circulatory failure and gestation continued until near term. In the neonatal period, we did a repeat valvuloplasty with systemic-to-pulmonary arterial shunt. Both children (now aged 18 months and 12 months) now have biventricular circulation. Surgery on selected fetuses with semilunar valve stenosis or atresia, or both, can extend pregnancy and favourably change the postnatal surgical options.