The NICE guideline on intrapartum care identified eight cross-sectional studies assessing parity as a risk factor for PPH, and recommended that grand multiparas (parity 4 or more) should be advised to give birth in an obstetric unit where more emergency treatment options are available. The included studies are described as:
“Three of them were conducted in the UK, three were in the USA, and two in Australia.
One US study investigated effect of parity on obstetric risk factors in 133 great-grandparous (defined as parity more than ten), 314 grandparous and 2195 parous women. Although the study reported significant increased incidence of PPH in grandparous than parous women, the analysis did not control important confounding factors such as age and hence is inconclusive.
One control-matched study in the UK was identified, which compared 397 grandparous women with 397 age-matched parous women to investigate effect of parity on obstetric risk factors. The study reported that there was no evidence of difference in incidence of PPH between these two groups (OR 1.18 [95% CI 0.6 to 2.4]).
One Australian study was conducted between 1974 and 1975 to investigate obstetric performance of grand multiparous women. Although the study reported no evidence of difference in incidence of PPH by parity, the analysis did not control confounding factors and hence is inconclusive.
One UK study was published in 1987, compared 216 grandparous women with lesser parity matched for age and ethnicity. There was a higher incidence of developing PPH (blood loss greater than 500 ml) for grandparous women compared with parous women (P < 0.01), although there was significant difference in gestational age at booking.
One Australian study was conducted between 1992 and 2001. The study investigated obstetric risk of 653 grand multiparous women, compared with 15 255 women with lower parity. Multivariate logistic regression analyses showed borderline increased risk of developing PPH by high parity (OR 1.36 [95% CI 0.99 to 1.87]).
One UK study investigated obstetric risk of 229 grand multiparous women with controls matched for age with one parity, between 1990 and 1991. The study reported no evidence of difference in incidence of PPH, although the proportion of women who had oxytocin administration in the third stage was different and hence the analysis was inconclusive.
One US study investigated obstetric outcomes of 382 grandparous women, compared with agematched controls with parity of between two and four, between 1989 and 1991. There was no evidence of difference in incidence of PPH between these two groups (OR 0.97 [95% CI 0.57 to 1.63]).
A third US study investigated perinatal outcomes of 25 512 grandparous women, compared with 265 060 parous women aged 30 years or greater between 1997 and 1998. Multivariate logistic regression analysis showed increased risk of developing PPH by grand multiparity, compared with multiparity (adjusted OR 1.2 [1.1 to 1.3]).
A second UK study investigated complications of the third stage of vaginal birth among 36 312 women between 1967 and 1981. There was evidence that higher incidence of PPH in nulliparous women and after induced labour. Analysis of the risks of 6615 women with two or three live births between 1967 and 1980 showed women with a history of PPH and/or retained placenta had higher risks of PPH in a subsequent birth, by between two and four times as much, compared with women without such a history.”
Subsequently published studies have reached varying conclusions, identifying nulliparity (Biguzzi, Ford), primiparity (Ben Hmid, Kramer, Malkiel) or high parity (Jaleel, Shaheen) as risk factors for PPH.
(Evidence level III)
Classification of evidence levels
- Ia: Evidence obtained from meta-analysis of randomised controlled trials.
- Ib: Evidence obtained from at least one randomised controlled trial.
- IIa: Evidence obtained from at least one well-designed controlled study without randomisation.
- IIb: Evidence obtained from at least one other type of well-designed quasi-experimental study.
- III: Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case studies.
- IV: Evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities.
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