| Type of population |
The size of groups 1 and 2 (39.5%) is within the expected range. However, the ratio of the size of group 1vs that of group 2 is very high (20.1). In the WHO Multicountry Study reference population (population in the WHO study with relatively low CS rates as well as good labour and childbirth outcomes), this ratio was found to be 6.3.27 43 Similarly, the ratio of the size of group 3vs that of group 4 is 21.6—very high compared with 6.3 in the WHO study.27 43 Both high rates probably indicate the need to increase inductions in these groups of women (term with singleton fetus in cephalic presentation) or even to avoid performing pre-labour CS. This is consistent with the high CS rates found in groups 1 and 3 and our data on stillbirth and neonatal deaths. Despite their being lower-risk groups, 37 (24%) and 29 (19%) of the total 152 perinatal deaths that occurred during the study period were in groups 1 and 3, respectively. Only group 10 had a larger number of perinatal deaths with 39 (25.7%) but this is a high-risk group where the women had singleton pregnancies in cephalic presentation preterm. The size of groups 3 and 4 is 33.9%. Since Tanzania has a high fertility rate, we expected a higher number of multiparous women. This can be explained by the very high size of group 5 (15.4%) with a CS rate of 87%, which contributes to about 38% of all the CS performed in the hospital. The size groups 6 and 7 is 1.6%, which is below the expected range for breeches. Moreover, the ratio of group 6/group 7 (0.5) is unusual since breeches are more frequent in nulliparas than multiparas. This could indicate errors in data collection potentially due to misclassification of nulliparous women with breech presentation into group 1. The size of group 10 is 6.2% that is slightly higher than that proposed by Robson (5%) and that found in the WHO Study (4.2%). Even if Tosamaganga Hospital is a referral hospital, only 168 women (5.6%) were referred, 107 (63.7%) of whom delivered by CS. For this reason, we consider that the larger sizes of groups 8 and 10 cannot be justified by a particularly high-risk population. Malnutrition and other concurrent diseases may have caused growth retardation and errors in pregnancy dating based on neonatal weight.
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| Caesarean section rate |
In all groups, the CS rates are higher than the expected range.27 43
It has been proposed that CS rates in group 1 of about 10% are achievable. However, the above-mentioned high ratio of group 1vsgroup 2 may be responsible for the high CS rate(27.4%) in this group. If insufficient numbers of women are induced or have necessary pre-labour CS, it is more likely that these women will need a CS at a later stage of labour. In addition, the high CS rate in group 2 is not caused by the size of group 2b (pre-labour CS, only 0.8% of the population), but mainly by a very low size of group 2a (1.1% of the population) and by the poor success for induction with a consequent high C/S rate (34.4%) in this group as well. Similar arguments apply to groups 3 and 4. The high CS rate in group 4 (55.5%) is not justified by the high size of group 4b (which accounted for only 0.8% of the population), but by the small size of group 4a (just 0.7% of the population). Particularly in groups 1 and 3, a large number of CS were performed with the diagnosis of dystocia. This might indicate a poor quality of diagnosis of dystocia and suboptimal management of the active phase of labour. The very high CS rate in group 5 (87.2%) is not justified by the proportion of women with two or more CS (group 5.2) who make up one-third of this group. CS rates in women with one CS (group 5.1) and two or more CS (group 5.2) are both high (83.2% and 97%, respectively), indicating the common practice of performing CS in women with previous scar. These rates contrast markedly with the 50%–60% rates considered appropriate by the Robson guideline and the 74.4% found in the WHO Study.27 43 Nevertheless, an assessment of the hospital’s capacity to offer safe trial of labour after CS (TOLACs) is crucial prior to making recommendation that more women be offered one VBAC was minimally practiced probably due to the inadequate number of midwives available to attend women in labour. Moreover, the lack of information regarding previous caesarean deliveries (how they were performed and whether or not complications occurred) may have exacerbated doctor’s fear regarding whether to offer a TOLAC. Looking at the higher-risk groups, the CS rate in group 8 is within the expected range, while the CS rate in group 10 is lower than expected, probably indicating a high rate of spontaneous preterm labour or a high incident of low birth weight (since newborn weight was used as a proxy for gestational age).27 43
Considering the contribution of the groups to the overall CS rate, groups 1, 2 and 5 account for 70.6% of all CS, a higher percentage than expected, and of that figure, group 5 accounts for 38.1% indicating, as already mentioned, a very high CS rate in the previous years.
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