Elite Athletes and Pregnancy Outcomes: A Systematic Review and Meta-analysis.

Purpose The purpose of this systematic review was to evaluate fetal and maternal pregnancy outcomes of elite athletes who had participated in competitive sport immediately prior to conception. Methods Online databases were searched up to March 24, 2020. Studies of any design and language were eligible if they contained information on the relevant population (pregnant women), exposure (engaged in elite sport immediately prior to pregnancy), and outcomes (birthweight, low birthweight, macrosomia, preterm birth, fetal heart rate and pulse index, cesarean sections, instrumental deliveries, episiotomies, duration of labor, perineal tears, pregnancy induced low back pain, pelvic girdle pain, urinary incontinence, miscarriages, prenatal weight gain, inadequate/excess prenatal weight gain, maternal depression or anxiety). Results Eleven unique studies (n = 2,256 women) were included. We identified 'low' certainty evidence demonstrating lower rates of low back pain in elite athletes compared to active/sedentary controls (n = 248; OR 0.38; 95%CI [0.20, 0.73], I= 0%;); and 'very low' certainty evidence indicating an increased odds of excessive prenatal weight gain in elite athletes versus active/sedentary controls (n = 1,763; OR 2.47; 95%CI [1.26, 4.85], I= 0%). 'Low' certainty evidence from two studies (n=7) indicated three episodes of fetal bradycardia following high intensity exercise that resolved within 10 minutes of cessation of activity. No studies reported inadequate gestational weight gain or maternal depression or anxiety. There were no differences between elite athletes and controls for all other outcomes. Conclusion There is 'low' certainty of evidence that elite athletes have reduced odds of experiencing pregnancy-related low back pain and 'very low' certainty of evidence that elite athletes have increased odds of excessive weight gain compared to active/sedentary controls. More research is needed to provide strong evidence of how elite competitive sport prior to pregnancy impacts maternal and fetal outcomes. PROSPERO registration (CRD42020167382).