Authors (including presenting author) :
Shu W (1), Chan WL (1), Yeung APC (1)
Affiliation :
(1) Obstetrics and Gynaecology, Pamela Youde Nethersole Eastern Hospital
Introduction :
Induction of labour (IOL) is medically indicated when prolonging the pregnancy exerts comparatively higher risk to the pregnant women and/ or their fetuses, balancing against the risk of the IOL. When compared with natural onset of labour, IOL is associated with a longer duration of labour, and the possibility of Caesarean section (CS) for failed IOL or non-reassuring fetal status. In addition, the use of pharmacological agents to prepare the cervix and / or for stimulation of uterine contractions can lead to increase morbidity such as uterine hyper-stimulation, and fetal hypoxia.
Objectives :
This research aims at studying the trend of IOL in the eight birthing hospitals under Hospital Authority between 1999 to 2019.
Methodology :
All the details of each delivery, whether IOL was performed or indications behind it, is recorded into a dedicated OBSCIS system. Since 1998, the Quality Assurance Subcommittee of the Coordinating Committee (Obstetrics and Gynaecology) has published annual obstetric reports, drawing data form the OBSCIS system and compiling the results. This research retrieves all the reports and analyzes the total number of IOL, the percentage in each birthing hospital, the indications and the final modes of delivery. The contribution of IOL in emergency CS is also studied. In 1998 report, the two quoted total number of IOL did not match and is therefore excluded in this analysis.
Result & Outcome :
From 1999 to 2019, there were a total of 816,103 maternities who delivered in Hospital Authority, with 71,047 elective CS when IOL must not be required. The overall rate of IOL was 28.1%. This rate steadily increased from 21.2% in 1999 to 40.4% in 2019. Since 2002, the rates of IOL in individual birthing hospitals have also been reported. All demonstrated gradual increase of the rates. The lowest jumped from 9.9% in 2002 to 20.8% in 2019 while the highest also climbed from 30.4% to 45.5% in the same period.
Three indications for of IOL were reported in every annual reports. The most common is the prolonged rupture of membranes, which remained rather similar at about one-third throughout the third decades. The second most common reason is the post-maturity which reduced gradually from about a quarter initially to about 15% lately. Suboptimal CTG, which is sensitive but nonspecific for fetal hypoxia, is another indication with similar rates during the study period, averaging about 6%. Indication reported as "others" ranged from 36.8% to 65.8%. Only in 3 years (2015, 2016 and 2019) were additional indications reported, such as diabetes, hypertension, antepartum haemorrhage, intrauterine growth restriction, oligohydromnios and multiple pregnancy. The rates of the former three were even higher than the routinely reported suboptimal CTG.
The final mode of delivery being CS has been relatively stable, ranging from 20.7 to 25.6%. However, among all pregnant women who had emergency CS, those who had undergone IOL increased form about 35% initially to 50% in 2019, a rise of about 40%, which is even more faster than the rise of emergency CS rate of 20%.
