Fetus-Placenta-Newborn
Parity and pregnancy outcomes,☆☆

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Abstract

Objective: The issue of parity and risk of pregnancy outcomes has been controversial for many decades. We conducted a study to evaluate the association between parity and pregnancy outcomes and to clarify the basis of the classification of risk based on parity. Study Design: The study is a cross-sectional analysis on a large routinely collected data set of singleton births from 1992 to 1997 in New South Wales, Australia. Pregnancy outcomes were compared among parity groups. Results: There was a significant association between different parity levels and pregnancy outcomes in terms of obstetric complications, neonatal morbidity, and perinatal mortality, after adjustment for potential confounders, including age, maternal smoking status, and socioeconomic status. In terms of obstetric complications, neonatal morbidity, and perinatal mortality, subjects can be classified into 3 groups according to parity: nulliparity, low multiparity (parity 1, 2, and 3), and grand multipara (parity 4 to 8). Compared with low multiparity, mothers and babies of nulliparity and grand multipara are at higher risk. Conclusions: This study supported the definition of grand multiparity that should start from parity 4 or the 5th baby. Attention should be paid to subjects of nulliparity and grand multiparity for their different problems. (Am J Obstet Gynecol 2002;186:274-8.)

Section snippets

Material and methods

The New South Wales Midwives Data Collection (MDC) is a population-based surveillance system that covers all births in New South Wales, Australia. It encompasses all births of at least 20 weeks gestation or at least 400 g birth weight.10, 11 The MDC data was collected with the use of a standardized form for all New South Wales births. The data include demographic details and information of maternal health, pregnancy, labor, delivery, and perinatal outcomes.

During the period of 1992 and 1997,

Results

Of 510,989 study subjects, 40% were nulliparous; the proportion of multiparous women with parity 1 through 6 and 7 to 8 were 33.6%, 16.7%, 6.2%, 2.1%, 0.8%, 0.3%, and 0.2%, respectively (Table I).Table I also compares the sociodemographic characteristics of the study subjects between the different parity groups. The mean maternal age increased linearly with the increasing of parity (P <.001). There was a significant difference between private health insurance status and parity (P <.001); the

Comment

The major finding of this study is that, in this population, subjects with different parity are at different maternal and neonatal risks. Subjects can be classified into 3 groups according to their parity: nulliparity, low multiparity, and grand multiparity, in respect to the differences of the statistics of obstetric complications, neonatal morbidity, and perinatal death. By low multiparity, we mean parity 1, 2, and 3 (the delivery of the second to fourth baby). By grand multiparity, we mean

Acknowledgements

We thank the Epidemiology and Health Services Evaluation Branch, New South Wales Health Department, for providing access to the New South Wales Midwives Data Collection.

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Supported by the Health Research Foundation of Sydney South West.

☆☆

Reprint requests: Jun Bai, MPH, Division of Women’s and Child Health, Liverpool Hospital, NSW Australia, Locked Bag 7103, Liverpool BC NSW 1871, Australia. E-mail: [email protected]

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