Trends in births at and beyond term: evidence of a change?

Abstract

Objective To examine trends in the distribution of births at and beyond term in New South Wales and in particular, to determine whether any changes are associated with changes in the obstetric practices of induction and elective caesarean section. Design Cross‐sectional analytic study. Setting New South Wales, Australia. Population All 540,162 women delivering a singleton cephalic‐presenting infant of gestational age ≥ 37 weeks from 1 January 1990 to 31 December 1996. Methods Data were obtained from the New South Wales midwives data collection, a population‐based surveillance system covering all births in New South Wales. The data were analysed to examine changes over time and associations between gestational age, maternal factors and onset of labour. Main outcome measures Induction of labour and elective caesarean section rates. Results From 1990 to 1996 there was a significant decrease in births reported as 40 weeks of gestation, from 35,670 (46.3%) to 30,651 (40.3%). These declines were offset by significant increases in births at 38 and 39 weeks. Births ≥ 42 weeks declined from 3321 (4.6%) to 2132 (2.8%). The decline in prolonged pregnancies was associated with increasing induction rates at 41 weeks. The re‐distribution of some births from 40 to 38–39 weeks was associated with increasing rates of elective caesarean sections and induction at 38 and 39 weeks, and increasing maternal age. Conclusions Clinicians appear to be implementing the recommendations of randomised controlled trials to offer induction after 41 weeks of gestation. However the trend of performing elective caesarean sections at earlier gestational ages may be unnecessarily putting some infants at increased risk of respiratory morbidity.

Variation in rates of postterm birth in Europe: reality or artefact?

“…2,3 Systematically proposing induction is a long-standing policy in many countries, including France and Canada; 2,4 in 2004, the American College of Obstetricians and Gynecologists updated their guidelines to promote a policy of systematic induction more actively but recommended that women 'with unfavourable cervixes can undergo labour induction or be managed expectantly'. 5 Studies from Australia, Canada, and the USA report recent rates of births after 41 weeks of gestation, [6][7][8] but European data on these rates are not available. This analysis uses populationlevel data on gestational age to compare rates of births at 42 weeks of gestation or later in European countries; these data were collected as part of the PERISTAT project on perinatal health indicators.…”

Shortening of gestational length among native-born and immigrants in Spain (1997–2008)

“…Trends of gestational shortening have been reported in other countries [17][18][19][20] . A study carried out in Australia 17 including births from 1990 to 1996 showed a decline in 40 and .…”

“…At the clinical setting, programs to reduce post-term pregnancies, better survival of increasingly premature births, increase of fertility treatments and obstetrical procedures such as elective caesarean section or elective induced labor are all factors that contribute to reduce the average duration of gestational age at birth in a population 1,[14][15][16] . The coexistence of many of these factors in current industrialized societies could be the explanation for the shortening of the gestational length identified in some recent studies [17][18][19][20] .…”

Shortening gestational age at term and organisation of birth care in the Czech Republic

“…A trend of shortening duration of pregnancies carried to term has been observed in several countries . Gestational age is an important predictor of the newborns' future health and development.…”

“…While this can be interpreted as an artefact, the use of obstetric interventions is not. Studies that tested the relationship between the mode of delivery (spontaneous vs induced onset, vaginal vs CS) and gestational duration found the increasing use of induction and CS as an important substantive explanation for the shortening gestational age …”