The study included all pregnant women aged 35 and older who delivered a viable fetus (≥28 weeks of gestation) or experienced intrauterine fetal death during the study period. Incomplete records, pregnancies terminated before 28 weeks, and women referred immediately postpartum were excluded. A total of 234 pregnant women of advanced maternal age were included in the analysis.

Independent variables were grouped into three categories:

The dependent variable was maternal outcome (favorable/adverse).

Using a standardized data collection sheet, data were extracted from interviews with the pregnant women during prenatal visits, prenatal care booklets, delivery registers, maternity obstetric records, and postnatal surveillance sheets. Each record was reviewed by two independent investigators to minimize transcription bias.

Data were analyzed using SPSS version 26.0. Quantitative variables were summarized by mean ± standard deviation, and qualitative variables by frequencies and percentages. The association between independent variables and maternal outcomes was studied using the χ² test or Fisher’s exact test, depending on the sample sizes. Odds ratios (OR) with their 95% confidence intervals (CI) were calculated in univariate analysis. Variables significant at p < 0.20 were entered into a multivariate logistic regression model to identify independent factors for adverse outcomes. The model’s quality was verified using the Hosmer-Lemeshow test and the area under the ROC curve (AUC).

The study received authorization from the management of Laquintinie Hospital. Data confidentiality was strictly maintained, and the information was anonymized before analysis. No direct interventions were conducted on the patients, as the study relied solely on clinical records.

Maternal complications affected 20.5% of women overall, with a clear age gradient (16.4% at 35 - 39 years → 50% at ≥ 45 years). Maternal mortality reached 3.4%, concentrated among women aged ≥ 40, unemployed, or with a low level of education. Unemployed women and those with primary education had the highest rates of complications, 28.4% and 38.5% respectively, and mortality rates of 6% - 8%, reflecting the impact of socioeconomic determinants on maternal prognosis ( Table 1 , Figure 1 ).

*χ² test or Fisher’s exact test according to frequencies. Significant if p < 0.05.

Maternal complications were significantly more frequent among pregnant women with a medical history (36.1% vs. 17.7%, p = 0.02). Similarly, a history of cesarean section significantly increased the risk of complications (33.9% vs. 15.7%, OR = 2.22 (1.13 - 4.36), p = 0.01). Maternal mortality, although rare (3.4%), mainly concerned grand multiparas and hypertensive patients. These associations confirm the aggravating role of medical and surgical histories in the prognosis of pregnancies at advanced age.

Figure 2 illustrates the odds ratios (OR) of the main obstetric and medical variables associated with adverse maternal outcomes in women of advanced maternal age in Douala. Several histories were observed to significantly increase the risk of complications:

Overall, the figure reflects an increasing gradient of maternal risk in the presence of medical or surgical histories, particularly hypertension and prior cesarean section, two major determinants of the complications observed in this cohort of advanced-age pregnancies ( Table 2 , Figure 2 ):

*χ² test or Fisher’s exact test according to frequencies. Significant if p < 0.05. ** Others = asthma, diabetes, sickle cell disease, hepatitis B, obesity, epilepsy.

Adverse outcomes were significantly more frequent among women with insufficient prenatal care (<1 prenatal visit/month), absence of malaria prophylaxis (IPT), or lack of calcium supplementation (p < 0.01). The occurrence of a pathology during pregnancy tripled the risk of complications (OR = 3.32; 95% CI = 1.64 - 6.72), primarily dominated by gestational hypertension (OR = 3.47; p = 0.002). Conversely, regular intake of calcium and aspirin seemed protective against maternal complications ( Table 3 , Figure 3 ).

*Significant if p < 0.05.

After adjusting for the significant variables in univariate analysis, the factors independently associated with adverse maternal outcomes were ( Table 4 ):

Conversely, regular intake of calcium had a protective effect (OR = 0.42 (0.20 - 0.90); p = 0.024).

The final model showed good calibration and satisfactory discrimination (AUC = 0.82).

Hosmer–Lemeshow Test: χ² = 6.18; p = 0.63 (good calibration), Area under the ROC Curve = 0.82 (good model discrimination), *Significant if p < 0.05.

The observed complication rates are consistent with those reported in other African contexts. In Rwanda, Benimana et al. (2020) found severe maternal morbidity in 19.8% of women ≥ 35 years old, compared to 12.1% in younger women [11] . In Ethiopia, Abate et al. (2021) reported an increased risk of preeclampsia and postpartum hemorrhage beyond the age of 40 [12] . The association between advanced maternal age and adverse outcomes is explained by reduced cardiovascular and uterine adaptive capacity, the increased frequency of chronic pathologies, and decreased myometrial contractility. Several meta-analyses confirm a doubling of the risk of preeclampsia, hemorrhage, and cesarean section from the age of 40 [3] [15] . Medical history and previous cesarean section act through distinct mechanisms: the former reflects an underlying pathological condition, whereas the latter indicates prior obstetric morbidity and an increased likelihood of surgical complications in subsequent pregnancies.

A history of cesarean section also doubles the risk of maternal complications due to scar tissue and intraoperative complications (adhesions, uterine rupture, hemorrhage). Similar results were observed in Cameroon by Njamen et al. (2021) [16] and in the WHO multicenter study (Laopaiboon et al. 2014) [6] . Medical history (hypertension, HIV, diabetes) was associated with a two-fold increased risk in our study. This finding is consistent with that of Bukar et al. in Nigeria [17] and Ganchimeg et al. (2014) [10] , showing that pre-existing comorbidities worsen obstetric prognosis in older women.

On the socioeconomic level, unemployed or low-educated women presented more complications, probably due to late access to care, lower adherence to prenatal care and a lack of health knowledge. These social determinants have also been identified in Ghana [18] and Senegal [19] as indirect factors of maternal mortality. Finally, pregnancy-related pathology, particularly hypertension, emerged as the most powerful determinant in the model. This link is well documented in the literature: pregnancy-related hypertension is responsible for approximately 20% of maternal deaths in sub-Saharan Africa [20] [21] .

These associations reflect the clinical reality of Douala maternity wards, where older women combine several vulnerabilities: medical history, previous cesarean sections, and sometimes incomplete prenatal monitoring. Decreased uterine compliance and metabolic reserves, endothelial damage, and an increased inflammatory response explain the frequency of hypertensive and hemorrhagic disorders in this age group [7] . The socioeconomic context also plays an aggravating role: some women delay their first ANC or discontinue supplementation due to lack of means, which increases avoidable morbidity. The protective effect of calcium observed here corroborates the WHO (2011) recommendations [22] , which recommend daily supplementation of 1.5 - 2 g/day to reduce the risk of preeclampsia by 50% in populations with low dietary intake. In the Cameroonian context, this measure should be systematically integrated into antenatal care protocols, particularly for women over 35 years.

The main strength of this study lies in the combination of a rigorous analytical approach and a representative sample of older pregnant women. Logistic regression made it possible to identify independent determinants while controlling for confounding factors. Although prospective, the study may have been subject to information bias related to patient self-reporting of medical history. Some potentially important variables, such as BMI or reference time, were not available. Finally, the limited size of certain subgroups (≥45 years, grand multiparous women) reduces the statistical power of certain associations.

These results call for strengthening maternal risk stratification from the first ANC visit, by identifying women aged ≥40 years or with a history of medical or surgical complications. Routine calcium supplementation, blood pressure control, and prevention of hypertensive complications should be integrated into local protocols. In the medium term, the implementation of a predictive obstetric risk score in older women could help direct patients to the appropriate levels of care. Finally, prospective multicenter studies would validate these results and explore the interactions between social, biological, and obstetric factors in the occurrence of adverse outcomes.