***TASK***
the task is to simplify the input abstract of a biomedical literature

***INPUT***
the input is the abstract of a biomedical literature

***OUTPUT***
the output is the simplified abstract for the input abstract of a biomedical literature

***DOCUMENTATION***

***EXAMPLES***

Input: We included 14 trials involving 1014 women. The trials were small and not of high methodologic quality. Of the nine trials reporting on physical fitness, six reported significant improvement in physical fitness in the exercise group, although inconsistencies in summary statistics and measures used to assess fitness prevented quantitative pooling of results. Eleven trials reported on pregnancy outcomes. A pooled increased risk of preterm birth (risk ratio 1.82, 95% confidence interval (CI) 0.35 to 9.57) with exercise, albeit statistically non-significant, does not cohere with the absence of effect on mean gestational age (mean difference +0.10, 95% CI -0.11 to +0.30 weeks), while the results bearing on growth of the fetus are inconsistent. One small trial reported that physically fit women who increased the duration of exercise bouts in early pregnancy and then reduced that duration in later pregnancy gave birth to larger infants with larger placentas. Regular aerobic exercise during pregnancy appears to improve (or maintain) physical fitness. Available data are insufficient to infer important risks or benefits for the mother or infant. Larger and better trials are needed before confident recommendations can be made about the benefits and risk of aerobic exercise in pregnancy.
Output:

Aerobic exercise is physical activity that stimulates a person's breathing and blood circulation. The review of 14 trials, involving 1014 pregnant women, found that pregnant women who engage in vigorous exercise at least two to three times per week improve (or maintain) their physical fitness, and there is some evidence that these women have pregnancies of the same duration as those who maintain their usual activities. There is too little evidence from trials to show whether there are other effects on the woman and her baby. The trials reviewed included non-contact exercise such as swimming, static cycling and general floor exercise programs. Most of the trials were small and of insufficient methodologic quality, and larger, better trials are needed before confident recommendations can be made about the benefits and risks of aerobic exercise in pregnancy.