Introduction
Since 19851, the World Health Organization (WHO) has
considered the ideal caesarean section (CS) rate to be between 10% and
15% with the crude rate of CS proposed as a global indicator to
evaluate the quality of obstetric care. However, since then, CS rates
have gradually increased, raising concerns on the potential negative
effects on mother and infant health, and many efforts have been made to
reduce the number of unnecessary interventions. In 2001
Robson2 proposed the “Ten Group Classification
System” (TGCS), a totally inclusive and mutually exclusive
classification system that divides the obstetric population into 10
groups with the aim of comparing caesarean section rates over time in
one single unit and among different units, to improve perinatal care. In
20173 the WHO has endorsed the TGCS, proposing that it
should be considered “a global standard for assessing, monitoring and
comparing CS rates within healthcare facilities over time, and between
facilities”. A relatively recent review4 of the
literature that included 73 papers on the use of the Robson
classification in more than 33 million women in 31 countries showed
that, despite its valuable utility, among the limitations reported by
users, there was a failure to take into account the indication to the CS
and the characteristics of both the mother and the fetus, which can
significantly influence the CS rate (e.g. maternal age or fetal growth,
to name just a few). Consequently, it is possible to find different CS
rates in the same Robson group, in relation to different countries, but
also in the same institution, in relation to different types of women.
These differences may influence the comparison among hospitals or inside
the same hospital if the population characteristics change. Maternal
age, immigrant status, body mass index and diseases (for instance,
gestational diabetes mellitus or hypertension), or neonatal birthweight
and the use of obstetric analgesia are not taken into consideration by
the TGCS but they potentially influence the CS rate. Our hypothesis is
that these factors may influence the probability of giving birth by
caesarean section, within each individual Robson group.
Therefore, the purpose of our study was to evaluate which obstetric and
maternal-fetal variables affect the CS rate within the individual Robson
groups and to verify any differences between the groups. As secondary
results we analysed the time course of the CS rate for the Robson groups
over a period of 24 years.