A comparison of fetal behaviour in breech and cephalic presentations at term

To evaluate fetal behaviour in breech and cephalic fetuses at term, using a computerised fetal behaviour program.

An observational study.

Pregnancy Assessment Centre, University Hospital, Nottingham.

Twenty-six breech and 58 cephalic fetuses between 36 and 41 weeks.

Behaviour (fetal heart rate and activity) was recorded with the use of Doppler ultrasound. The duration of recording was 60 minutes or more in all but four recordings (minimum 49 minutes).

Behavioural criteria studied were 1. the relative percentage time spent in low and high variation fetal heart rate patterns; 2. the duration and recurrence of fetal activity; 3. the number of accelerations in low and high fetal heart rate variation; and 4. the number of fetal behavioural state transitions.

Breech fetuses differed from the cephalic group in that they were lighter than the cephalic fetuses (median 3105 g vs 3400 g; P < 0.01) and were born to older mothers (median maternal age 30 years vs 28 years; P < 0.01). No significant differences were found in rates of movement, numbers of accelerations and time exhibiting low and high fetal heart rate variation. However, breech fetuses exhibited significantly more state transitions (median 5.2/h vs 3.69/h; P = 0.01).

This study shows that breech fetuses are neurologically different from their cephalic counterparts in otherwise healthy pregnancies, and that subtle behavioural differences can be demonstrated in utero using this computerised method.