Postpartum anemia is common in both high- and low-resource settings and is linked to impaired maternal recovery and adverse maternal-infant outcomes [1]. The World Health Organization (WHO) defines postpartum anemia as hemoglobin 11 g/dL at one week or 12 g/dL at one year after delivery, typically resulting from uncorrected iron deficiency during pregnancy or significant peripartum blood loss [2]. In Latin America, prevalence among pregnant women has been reported between 20% and 39%, while pooled estimates in Ethiopia indicate a 27% prevalence of immediate postpartum anemia, underscoring the global persistence of this problem [3, 4]. Consequences include fatigue, cognitive impairment, postpartum depression, and disruptions in maternal-infant bonding, documented across diverse health-system contexts [5, 6, 7].

Regionally, studies from Latin America describe heterogeneous antenatal screening coverage and variable adherence to iron supplementation, with postpartum anemia persisting despite high facility-delivery rates [3, 8, 9]. In Peru, hospital-based work reports high postpartum anemia, particularly among women with antenatal anemia, inconsistent supplementation, or puerperal complications, and follow-up and patient education remain limited [8, 10, 11]. Similar gaps in postpartum laboratory monitoring have been observed in Uruguay and Spain, and severe postpartum anemia has been associated with rehospitalization, transfusion, and poor outcomes in cohorts from sub-Saharan Africa, the United States, and Norway [3, 6, 12, 13]. Together, these findings point to recurring deficits in follow-up, education, and system response despite established recommendations.

International guidance calls for routine screening and coordinated, multidisciplinary care; however, implementation is inconsistent, especially in low-resource settings [13]. Evidence from low- and middle-income countries highlights insufficient patient education, inconsistent supplementation practices, and limited postpartum care as persistent barriers [14, 15]. The lack of harmonized strategies for risk assessment, follow-up, and nutritional counseling reinforces the need for locally relevant research to clarify setting-specific risk factors and inform targeted interventions [15].

Evidence from military or other standardized-care health systems remains limited, particularly in Latin America. These systems follow uniform pathways, protocolized antenatal hemoglobin screening and iron-folate supplementation, immediate postpartum hemoglobin testing, and structured discharge counseling and patient profiles and resource flows may differ from civilian public hospitals. Estimates derived from mixed civilian cohorts may therefore not generalize to military institutions. To address this gap, we examined risk factors for immediate postpartum anemia within a standardized military care environment at the Central Hospital of the Peruvian Air Force.

In bivariate analyses, anemia during pregnancy showed a very strong association with immediate postpartum anemia, and women with postpartum anemia had fewer prenatal visits than controls. In the multivariable model, the number of prenatal visits was not statistically significant but suggestive (aOR = 0.86; 95% CI: 0.74–1.01; p = 0.060). Anemia during pregnancy could not be estimated because of perfect prediction; nevertheless, its bivariate contrast (25.5% vs. 0.0%; p 0.001) indicates the strongest factor in this cohort. The exclusion of anemia during pregnancy from the multivariable model reflects complete separation rather than a lack of effect. Given its 0.0% prevalence among controls and the large unadjusted contrast, this variable likely represents a dominant upstream determinant, consistent with prior literature. Larger studies could use penalized likelihood (e.g., Firth) to obtain adjusted estimates under separation; nonetheless, our findings support preventing and correcting antenatal anemia as a primary clinical priority.

Our finding of antenatal anemia as the dominant upstream factor, alongside a marginal inverse association for prenatal-visit number, aligns with reports from Latin American hospital cohorts and from standardized-care or military systems. In Uruguay’s military hospital population, pregnancy-related anemia has remained prevalent despite organized pathways [3]. Peruvian hospital-based studies similarly report high postpartum anemia, especially among women with antenatal anemia or suboptimal supplementation and limited follow-up [10, 11]. Outside Latin America, a multi-hospital study in Saudi Arabia identified antenatal anemia as the strongest predictor of postpartum anemia and found no independent effect for low prenatal-visit counts, consistent with our adjusted findings [18]. European evidence also underscores how system processes screening timing, monitoring, discharge education shape detection and management of postpartum anemia [6, 12].

Taken together, our results support a protocolized bundle for comparable standardized-care settings: (1) third-trimester hemoglobin screening with prompt correction of antenatal anemia; (2) reliable iron-folate supply with adherence support at each contact; (3) immediate postpartum hemoglobin testing (within 6 hours where this clinical trigger is used) coupled with structured discharge counseling; and (4) early follow-up within 1–2 weeks to reassess symptoms, reinforce adherence, and arrange intravenous (IV) iron when indicated. These steps mirror recommendations and implementation levers described in recent guidance and landscape reviews [12, 13, 15].

Fewer prenatal contacts can delay screening for antenatal anemia, reduce opportunities for counseling and refills of iron supplementation, and limit timely correction of deficiency mechanisms that plausibly increase immediate postpartum risk. Strengthening protocolized antenatal screening and adherence support may therefore mitigate postpartum anemia even where sociodemographic gradients are modest.

Findings regarding prenatal visits are heterogeneous across the literature. Several studies did not identify visit number as an independent predictor after adjustment, in line with our marginal adjusted result [18, 19, 20, 21]. By contrast, other reports observed higher risk with fewer or no visits: lack of antenatal care independently predicted postpartum anemia (aOR = 2.92; 95% CI: 1.20–7.06) in Agmassie et al. [22], and fewer than four visits increased the risk of immediate postpartum anemia (aOR = 3.18; 95% CI: 1.53–6.61) in Abebe et al. [23]. Alshahrani et al. [18], however, found no significant association when comparing 3 vs. $\ge$3 visits (p = 0.50). These discrepancies likely reflect differences in population characteristics, definitions of antenatal-care adequacy, timing of hemoglobin assessment, and health-system context such as the high baseline level of standardized care in our military cohort rather than contradictory biology. Taken together, the literature and our data emphasize prioritizing care-process quality screening timeliness, counseling intensity, and refill adherence over visit counts alone in prevention strategies.

Our results and prior evidence also underscore the central role of anemia during pregnancy. Strong adjusted associations have been reported across settings: preoperative anemia predicted postpartum anemia following cesarean section (aOR = 14.5; 95% CI: 4.11–51.16) in Habtamu et al. [19]; pre-delivery hemoglobin 11 g/dL independently increased immediate postpartum anemia (aOR = 5.46; 95% CI: 3.09–9.67) in Abebe et al. [23]; and pre-delivery anemia was the strongest predictor (aOR = 4.99; 95% CI: 1.84–13.50; p = 0.002) in Alshahrani et al. [18]. Liu et al. [24] further linked antenatal anemia with postpartum hemorrhage (p = 0.025), while one study did not confirm an adjusted effect [22]. Although our multivariable model could not estimate this predictor due to perfect prediction, the 25.5% vs. 0% contrast in our bivariate analysis confirms its dominant role and reinforces the clinical priority of preventing and correcting maternal anemia during pregnancy.

Null findings for education, parity, delivery type, and BMI have also been reported elsewhere. For education, several analyses did not identify a significant adjusted effect [18, 20, 21], whereas Abebe et al. [23] found that lack of formal education increased risk (aOR = 3.92; 95% CI: 1.85–8.33). Regarding parity, Alshahrani et al. [18] observed no association with postpartum anemia (p = 0.309) but noted greater anemia severity among women with only one previous delivery (p = 0.043), while Habtamu et al. [19] reported that primiparity was inversely associated with postpartum anemia after cesarean section (aOR = 0.47; 95% CI: 0.24–0.92). For mode of delivery, several studies including ours did not find an independent association [18, 19, 21], although others reported higher risk in specific contexts (e.g., prior cesarean section or cesarean delivery vs. vaginal birth: AOR = 3.40; 95% CI: 1.89–6.10 and aOR = 4.10; 95% CI: 2.11–7.78, respectively) [23, 25]. For BMI, Alshahrani et al. [18] found no relationship with postpartum anemia, and Liu et al. [24] noted that pre-delivery anthropometrics did not predict postpartum hemorrhage after adjustment. In our relatively homogeneous, standardized-care environment with high prenatal-care uptake, between-patient variability in these characteristics may be attenuated, shifting risk toward modifiable process measures (screening, supplementation adherence, discharge education).

In summary, this study identified the number of prenatal visits as the main factor associated with postpartum anemia among immediate postpartum women at a Peruvian Air Force Hospital. Other sociodemographic, obstetric, and clinical variables including educational level, multiparity, type of delivery, and body mass index were not significantly associated with postpartum anemia in this population. These findings underscore the crucial role of comprehensive and sustained prenatal care in reducing the risk of postpartum anemia. Strengthening antenatal surveillance and prioritizing the early detection and management of anemia during pregnancy should be central components of both clinical practice and public health strategies. Our results offer important local evidence that enriches the current understanding of postpartum anemia and highlight the need for context-specific interventions to improve maternal health outcomes in Peru and comparable settings.

The datasets generated and analyzed during the current study are not publicly available due to institutional and patient confidentiality policies, but are available from the corresponding author upon reasonable request.

CAMM and MAAH designed the research study. CAMM collected and curated the data. MAAH performed the formal analysis. CAMM and KAHB developed the study methodology. KAHB and MAAH supervised the research process. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript. All authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.

The study was conducted in accordance with the Declaration of Helsinki. The research protocol was approved by the Institutional Committee of Ethics and Scientific Integrity of Universidad Privada Norbert Wiener (Ethics Approval Number: Exp. N°: 0271-2025). Additional authorization for data collection was granted by the Department of Education, Teaching, and Research of the Central Hospital FAP (Approval Code: NC-50-HCDE-N°011). Informed consent was waived due to the retrospective nature of the study and the use of anonymized medical records without direct patient contact.

This research received no external funding.

The authors declare no conflict of interest.