***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: Results should be interpreted with caution because risk of bias of the included trials was variable. We included eleven new trials for this update; there are now 32 included studies, and one trial is ongoing. Thirty trials involving 9015 women contributed to the analysis. Comparisons include any upright position, birth or squat stool, birth cushion, and birth chair versus supine positions. In all women studied (primigravid and multigravid), when compared with supine positions, the upright position was associated with a reduction in duration of second stage in the upright group (MD -6.16 minutes, 95% CI -9.74 to -2.59 minutes; 19 trials; 5811 women; P = 0.0007; random-effects; I² = 91%; very low-quality evidence); however, this result should be interpreted with caution due to large differences in size and direction of effect in individual studies. Upright positions were also associated with no clear difference in the rates of caesarean section (RR 1.22, 95% CI 0.81 to 1.81; 16 trials; 5439 women; low-quality evidence), a reduction in assisted deliveries (RR 0.75, 95% CI 0.66 to 0.86; 21 trials; 6481 women; moderate-quality evidence), a reduction in episiotomies (average RR 0.75, 95% CI 0.61 to 0.92; 17 trials; 6148 women; random-effects; I² = 88%), a possible increase in second degree perineal tears (RR 1.20, 95% CI 1.00 to 1.44; 18 trials; 6715 women; I² = 43%; low-quality evidence), no clear difference in the number of third or fourth degree perineal tears (RR 0.72, 95% CI 0.32 to 1.65; 6 trials; 1840 women; very low-quality evidence), increased estimated blood loss greater than 500 mL (RR 1.48, 95% CI 1.10 to 1.98; 15 trials; 5615 women; I² = 33%; moderate-quality evidence), fewer abnormal fetal heart rate patterns (RR 0.46, 95% CI 0.22 to 0.93; 2 trials; 617 women), no clear difference in the number of babies admitted to neonatal intensive care (RR 0.79, 95% CI 0.51 to 1.21; 4 trials; 2565 infants; low-quality evidence). On sensitivity analysis excluding trials with high risk of bias, these findings were unchanged except that there was no longer a clear difference in duration of second stage of labour (MD -4.34, 95% CI -9.00 to 0.32; 21 trials; 2499 women; I² = 85%). The main reasons for downgrading of GRADE assessment was that several studies had design limitations (inadequate randomisation and allocation concealment) with high heterogeneity and wide CIs. The findings of this review suggest several possible benefits for upright posture in women without epidural anaesthesia, such as a very small reduction in the duration of second stage of labour (mainly from the primigravid group), reduction in episiotomy rates and assisted deliveries. However, there is an increased risk blood loss greater than 500 mL and there may be an increased risk of second degree tears, though we cannot be certain of this. In view of the variable risk of bias of the trials reviewed, further trials using well-designed protocols are needed to ascertain the true benefits and risks of various birth positions.
Output:

We searched for evidence up to 30 November 2016. This review now includes data from 30 randomised controlled trials involving 9015 pregnant women who gave birth without epidural anaesthesia. Overall, evidence was not of good quality. When women gave birth in an upright position, as compared with lying on their backs, the length of time they were pushing (second stage of labour) was reduced by around six minutes (19 trials, 5811 women; very low-quality evidence). Fewer women had an assisted delivery, for example with forceps (21 trials, 6481 women; moderate-quality evidence). The number of women having a caesarean section did not differ (16 trials, 5439 women; low-quality evidence). Fewer women had an episiotomy (a surgical cut to the perineum to enlarge the opening for the baby to pass through) although there was a tendency for more women to have perineal tears (low-quality evidence). There was no difference in number of women with serious perineal tears (6 trials, 1840 women; very low-quality evidence) between those giving birth upright or supine. Women were more likely to have a blood loss of 500 mL or more (15 trials, 5615 women; moderate-quality evidence) in the upright position but this may be associated with more accurate ways of measuring the blood loss. Fewer babies had problems with fast or irregular heart beats that indicate distress (2 trials, 617 women) when women gave birth in an upright position although the number of admissions to the neonatal unit was no different (4 trials, 2565 infants; low-quality evidence). This review found that there could be benefits for women who choose to give birth in an upright position. The length of time they had to push may be reduced but the effect was very small and these women might lose more blood. The results should be interpreted with caution because of poorly conducted studies, variations between trials and in how the findings were analysed. More research into the benefits and risks of different birthing positions would help us to say with greater certainty which birth position is best for most women and their babies. Overall, women should be encouraged to give birth in whatever position they find comfortable.