In accordance with the Robson classification of CS , which is accepted as the global standard for the monitoring of the CS indication spectrum , a previous CS birth and the breech presentation were confirmed as the highest risk factors for CS birth in Czechia (31-times higher odds of a CS birth for a breech position and 35-times higher odds of a CS birth for a breech position for multiparous women; 32-times higher odds of a CS birth following a previous CS birth) followed by multiple pregnancies (6-times higher odds and 9-times higher odds for multiparous women) and ART use (2-times higher odds). Our analysis also confirmed the importance of the other health and socio-demographic factors examined, i.e. they evinced statistical significance after adjustment for all the other covariates: gestational age, diabetes, complications in pregnancy and childbirth, the mother’s age, marital status and education. The differences in the risk of a CS birth according to marital status and education were statistically significant only for certain categories. A slightly higher risk of CS (1.6-times higher odds) was observed for single compared to married women, and a lower risk of CS (0.89-times lower odds) was observed for tertiary-educated women than for those with a secondary education. Our results confirmed the age factor as an independent risk with concern to a CS birth. With respect to the explanation for the increase in the CS rate in Czechia since the 1990s, both clinical (higher maternal ages at birth, an increase in ART use, multiple pregnancies) and non-clinical factors (health provider practices and guidelines, legislation) played noticeable roles.
Despite the use of a comprehensive dataset, the study has a number of limitations. The design does not allow for the causal interpretation of the associations studied. The covariates in the models were restricted to those available in the register. Information on education and marital status is not provided for all the women in the dataset; hence, for this part of the analysis, it was necessary to reduce the dataset by 21%, although no differences were observed between the two groups in terms of the structure of the mothers by age and CS births. Moreover, information on the use of ART methods was estimated based on information on ART cycles performed in Czechia only; foreign women and women who underwent ART abroad were thus classified as non-ART. Given that Czechia is more likely to be a destination country for cross-border reproductive care, we did not anticipate any bias in the results from this point of view. As for the explanatory factors, since we had no information on the maternal pre-pregnancy weight and height, we were unable to adjust for the body mass index.
Our results are consistent with literature in terms of reporting significant associations between the studied risk factors and a CS birth. It is reasonable to conclude that these factors have, to various extents, been behind the growth in the CS rate in Czechia since the 1990s. It is important to prevent the further growth in the CS rate and to determine the optimal percentage of CS, especially concerning the elective cesarean delivery of planned primarily indicated CS. It is clear that the underuse of CS results in hypoxic neonatal injury, stillbirth, uterine rupture and obstetrics fistulas , while the overuse of CS is associated with the increased risk of anesthesiologic and cardiovascular complications, infection complications and hysterectomy , as well as with adverse perinatal outcomes .
The incidence of serious complications is so rare due to advances in health care that many obstetricians lack the relevant experience. Nevertheless, the data clearly indicates a higher risk of morbidity and mortality as a result of a CS than a spontaneous delivery, even with respect to VBAC (vaginal birth after cesarean) . However, in Czechia many patients and some obstetricians appear to believe that the opposite is the case, as reflected by the fact that a previous CS was found to be a key risk factor for a subsequent CS. The fact that 71.2% of Czech women with a history of CS give birth again via CS serves to confirm the low chance of a VBAC in such cases. This is in line with another study that documented that a high percentage of births via CS are followed by a subsequent birth via the same method without the option of TOLAC (the trial of labor after cesarean) . Increased maternal age  also contributes to the indication of ERCS (elective repeat CS). Enforcing this practice in Czechia may also have contributed to the increase in the CS rate. The increase in women giving birth via CS in their first pregnancy results in an ongoing increase in the repeat CS birth rate . If the CS rate increases for first-time mothers, it can be expected that this will generate a higher proportion of repeat CS. Accordingly, it can be assumed that a change in practice has the potential to reduce the CS rate in Czechia .
A further reason for the increase in CS births concerns the move away from spontaneous delivery when the fetus is in the breech presentation. This trend, initiated by the Term Breech Trial Collaborative Group study , has gradually led to a decline in the experience of such births and, thus, to a further increase in the use of CS. This approach has begun to be applied consistently in Czechia and is frequently referred to in medical study materials. However, spontaneous delivery when the fetus is in the breech presentation remains inadvisable, especially in the case of pre-term births .
The literature shows that a number of maternal health risks are age-related and that the risk of a cesarean birth increases with the maternal age [23, 40, 41]. For example, older mothers are associated with higher risks of the incidence of diabetes mellitus , pre-term births [24, 43], lower child birth weights [20, 21, 44, 45] and pre-term births associated with diabetes mellitus [46, 47]. Mothers over 30 years of age also face the increased risk of child health complications, spend longer times in hospital following the birth and face a higher risk of more frequent and longer hospital stays in the first two years of the child’s life . The application of logistic regression confirmed that both pregnancy health complications (preterm-birth, diabetes, hypertension) and the mother´s age comprise independent risk factors for a CS birth. The Czech results confirmed that mothers who gave birth very pre-term (28–31 weeks) had 3-times higher odds of a CS than women who had an in-term birth . Mothers who suffered from diabetes before pregnancy had more than two-times higher odds of giving birth via CS than women who did not suffer from this condition, while mothers with gestational diabetes had 1.23-times higher odds; these results correspond to those of other published studies . As expected, mothers who suffer from hypertension gave birth via CS twice as often as did those with no such complications .
Furthermore, our results confirmed the age factor as an independent risk for CS birth. Similar results were reported in a British study , the sample population of which comprised 76,158 singleton pregnancies with a live fetus at 11 + 0 to 13 + 6 weeks. After adjusting for potential maternal and pregnancy confounding variables, advanced maternal age (defined as ≥ 40 years) was associated with an increased risk of cesarean section (OR, 1.95 (95% CI, 1.77–2.14); P < 0.001). A recent Danish study  showed that nulliparous women aged 35–39 years had twice the risk of a CS (adjusted OR, 2.18 (95% CI, 2.11–2.26); P < 0.001).
Thus, one of today’s most important population trends – fertility postponement – also comprises one of the significant independent factors associated with the risk of a CS birth. According to Timofeev et al. , the ideal age of mothers at birth is 25–29 years, at which time the risk of complications in pregnancy and the neonatal period is lowest. The increased risk of an adverse pregnancy is evident as early as between 30 and 34 years and continues to increase with age . The question thus concerns the age that marks the limit in terms of the increased health risks associated with the mother’s age. The association becomes significant from the age of 40 onwards , sometimes even after the age of 35 . In any case, the risks associated with age are of a progressive character [20, 41].
The highest fertility rate in Czechia in 2018 was attained by women aged 30, in contrast to the early 1990s when maximum fertility was attained at the age of 22 . The shift in fertility to older women in Czechia is further illustrated via a comparison of the share of fertility achieved by the age of 30. In 1989, the proportion stood at 86.6%, whereas by 2018 the share had dropped to 48.6% . Thus, the trend toward delayed childbearing is apparent in Czechia as a result of the second demographic transition [53, 54], which indicates that reverse changes in fertility trends are highly unlikely. Nevertheless, fertility postponement can be decelerated or halted by the introduction of effective measures that act to remove barriers to starting a family . To sum up, the strength of the association between advanced maternal age and CS and the fact that the trend in the share of CS births in Czechia has copied the trend in the mean age of mothers at childbirth (Fig. 1) support the hypothesis of a causal relationship between the maternal age and CS. However, as other factors come into play, further research is required so as to assess whether the recent slight decline in the CS rate is not merely a temporal trend.
A further risk factor that is closely connected with fertility postponement concerns the use of ART. Our results confirmed that mothers who most likely became pregnant following embryo transfer also had 1.83 higher odds of a cesarean delivery, even when controlling for the age, order and frequency of birth. According to the meta-analysis of the Medline, EMBASE and CINAHL databases , IVF/ICSI pregnancies are associated with a 1.90-fold increase in the odds of a CS (95% CI 1.76–2.06) compared to spontaneous conceptions. Since the late 1990s, Czechia has registered a significant increase in the use of ART and it has become a country with a relatively high proportion of ART live births [18, 19]. Accordingly, the increased use of ART in Czechia may have contributed to the explanation of the increase in the CS rate.
It is noteworthy that, despite the decline in marriage, marital status continues to comprise a relevant variable. In Czechia a slightly higher risk of CS (OR 1.06) was observed for single compared to married women despite the control of variables such as the age of the mother and the birth order. The higher risk of giving birth via CS for single women may be due to the fact that marital status is related to the health status, i.e. married persons have a higher level of self-esteem than do single people .
With regard to the level of the woman’s education, no significant differences were detected in terms of the risk of a CS between women with a basic but incomplete education, secondary without the SLC (school leaving certificate) and secondary with the SLC. The controlling of the age and other variables revealed lower odds of a CS birth (OR 0.89) for tertiary-educated women than those with the SLC. The higher odds of CS for women with lower levels of education could be explained by their working in riskier professions, a higher incidence of smoking or obesity or generally poorer living conditions . Conversely, tertiary-educated women are, in general, more open to practicing a healthy life style and receptive to the promotion of the benefits of natural childbirth in contrast to the numerous risks of CS for the subsequent health of both mothers and their children . Thus, the introduction of health education as a component of the antenatal care process as a form of non-clinical intervention should be considered aimed at reducing the unnecessary use of CS .
The trend toward an increase in CS in Czechia can also be understood from the legislation perspective, in particular with concern to the introduction of the new Civil Code in 2014, which replaced clearly-defined compensation levels for personal injury with the decision on the amount thereof being decided solely by the courts. The courts continue to maintain the misconception that CS is the best form of intervention in terms of assuring the health of the child and mother. A similar situation has been reported by Longo with respect to Italy [5, 60, 61].
The share of CS births in Czechia (23.6%) exceeds WHO recommendations of 2015 on the optimal proportion of CS births (10–15%). Based on our results, we doubt whether the WHO recommendations reflect the increasingly older ages of mothers, especially first-time mothers and the high degree of institutionalization of deliveries in developed countries. Trusting the delivery to physicians is usually accompanied by a significantly higher degree of monitoring, with the associated risks of false-positive indications of hypoxia, a higher rate of medication use, and the loss of faith in normal childbirth .
Some women prefer a CS since they consider it to be safer for both themselves and the baby, an opinion that runs contrary to current scientific knowledge. A history of CS is associated with a higher risk of uterus rupture, placenta accreta, ectopic pregnancy, stillbirth, pre-term birth, and bleeding and the need for a blood transfusion, injury during surgery and hysterectomy in subsequent pregnancies. A higher birth order CS also increases the risk of maternal mortality and morbidity compared to a vaginal delivery .
CS may also lead to enhanced health risks for the baby – altered immune development, the increased likelihood of allergies, atopy, asthma, a reduction in intestinal microbiome diversity  and late childhood obesity . The risk is higher for planned CS. Few studies have been conducted to date on the influence of CS on the cognitive and educational outcomes of CS-born children .
Thus, it is important that all the indications concerning birth via CS are carefully considered and that this method is not overused. Czechia makes no effort to contribute to efforts to reduce the percentage of cesarean sections; on the contrary, the reimbursement of costs by health insurance companies is higher for a cesarean section than for a spontaneous birth. One of the measures that might significantly prevent the expansion of CS use concerns a recommendation from the relevant professional authorities to strictly refuse cesarean sections on request . Although this recommendation has been mentioned frequently in various professional forums in Czechia , efforts persist internationally to enforce dubious indications for a CS birth such as the protection of the pelvic floor , which also enjoys some support in Czechia. Nevertheless, in Czechia, CS on request is not legally permitted. Furthermore, the implementation of clinical practice guidelines combined with a mandatory second opinion for a CS indication is also relevant to the reduced risk of CS in Czechia .
In conclusion, despite the international concern surrounding the increasing CS rate, the Czech CS rate decreased from 26.1% in 2015 to 23.6% in 2018. Interestingly, this has not been attributed to any particular Czech health strategy aimed at reducing the CS rate. Although it has been perceived as a significant success for the field of Czech obstetrics, further research is needed in order to assess whether this is not merely a temporal trend.
Meaning of the study: possible mechanisms and implications for clinicians and policymakers
Delayed childbearing appears to be associated with the increasing use of CS in parallel with the expansion of defensive obstetrics that imply a high risk of CS in cases of a breech presentation and following a previous CS. In addition, the increased use of CS also reflects social demand, an increasing trend toward the prosecution of obstetricians in the event of childbirth complications and the erroneous lay perception of CS as the safest and least painful childbirth method. On the other hand, clinical practice based on the official refusal of CS on request could well prevent the overuse of CS. As regards obstetric practice, measures to encourage TOLAC, albeit with a careful eligibility assessment, may also help to reduce CS. As regards non-clinical interventions targeted at women, the support of training programs and health education on the indications and contra-indications of CS may also serve to improve the CS rate.