Fetal wellbeing may be compromised during strenuous exercise among pregnant elite athletes

ArticleinBritish Journal of Sports Medicine 46(4):279-83 · March 2011with4 Reads
Impact Factor: 5.03 · DOI: 10.1136/bjsm.2010.080259 · Source: PubMed

    Abstract

    To study fetal wellbeing and uteroplacental blood flow during strenuous treadmill running in the second trimester.
    Six pregnant Olympic-level athletes in endurance events aged 28-37 years and training 15-22 h per week before the pregnancy were tested once at 23-29 weeks of pregnancy. The women ran three to five submaximal workloads on a treadmill with approximately 60-90% of maximal oxygen consumption. The maternal-fetal circulation was assessed with Doppler ultrasound of the uterine and umbilical arteries before, during and after exercise.
    Mean uterine artery volume blood flow was reduced to 60-80% after warming up and stayed at 40-75% of the initial value during exercise. Fetal heart rate (FHR) was within the normal range (110-160 bpm) as long as the woman exercised below 90% of maximal maternal heart rate (MHR). Fetal bradycardia and high umbilical artery pulsatility index (PI) occurred when the woman exercised more than 90% of maximal MHR and the mean uterine artery volume blood flow was less than 50% of the initial value. FHR and umbilical artery PI normalised quickly after stopping the exercise.
    Exercise at intensity above 90% of maximal MHR in pregnant elite athletes may compromise fetal wellbeing.