During the study selection process, a total of 1560 studies were identified through electronic searches of databases. After removing duplicates, 1432 studies conducted between 2010 and 2023 remained. Out of these, 1240 studies were excluded based on title screening alone. After reading the abstracts of the remaining 192 studies, 158 were further excluded. Finally, 34 studies underwent a full-text review, and 26 articles with a total of 35,226 study participants were selected for the analysis of the magnitude and/or determinant factors and its complication to short inter-pregnancy interval (Fig. 1).

Fig. 1

PRISMA flow diagram showed the results of the search and reasons for exclusion

Characteristics of included studies

Table one summaries the characteristics of twenty six included Studies in the Systematic Review and Meta-Analysis [15, 16, 26,27,28, 37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57]. 08 studies were found in Amhara region [26, 41,42,43, 45, 52, 56, 57]. 05 in Oromia region, 04 in south nation nationalities people region [16, 27, 46, 51, 53], 06 in Ethiopia from EDHS report and meta-analysis [38, 40, 44, 47,48,49], 02 in Tigray [54, 55] and 01 in Somalia region [28]. Most of the studies were published between 2013 and 2021. The studies included participants, ranging from 299 [57] to 8448 [38] (Table 1).

Table 1 Distribution of studies on the magnitude, determinant factors, and complications of short inter pregnancy interval among pregnant mothers (2010–2023)

Meta-analysis magnitude determinates factors and its complication of short inter pregnancy interval among pregnant mother in Ethiopia. Most of the studies (n = 15) had reported the magnitude short inter pregnancy interval [16, 27, 38, 40, 42, 44, 46,47,48,49,50, 53, 55,56,57]. The magnitude of short inter pregnancy interval was ranged from 6.0% [44] up to 59.9% [16]. The random-effects model analysis from those studies revealed that, the pooled magnitude of short inter pregnancy interval among pregnant mother in Ethiopia was found to be 44.054% (95%CI (32.735–55.372); I2 = 100% %; P < 0.001) (Fig. 2).

Fig. 2

The pooled magnitude of short inter pregnancy interval among pregnant mothers in Ethiopia

Subgroup analysis of the magnitude of short inter pregnancy interval among pregnant mother in Ethiopia

The subgroup analysis conducted in this meta-analysis involved stratifying the studies based on region, sample size, and year of publication. By doing so, the researchers were able to examine the magnitude of short inter pregnancy intervals among pregnant mothers in Ethiopia more closely. The results of the analysis revealed that the estimated magnitude of short inter pregnancy intervals among pregnant mothers in Ethiopia was found to be 44.054% (95% CI 32.735–55.37) (Fig. 2). Based on the subgroup analysis stratified by study region, the magnitude of short inter pregnancy intervals among pregnant mothers was found to be 57.00% (95% CI 56.885–57.115) in the South Nation and Nationality, 38.502% (95% CI 20.434–56.569) in Ethiopia EDHS data and meta-analysis, 54.048% (95% CI 50.246–57.85) in the Oromia region, 44.432% (95% CI 38.688–50.175) in the Amhara region, and 23.3% (95% CI 23.197–23.403) in the Tigray region (Fig. 3, Supplementary Table 1).

Fig. 3

Subgroup analysis of the magnitude of short inter pregnancy interval among pregnant mothers in Ethiopia by region category

Based on the study sample size, the magnitude of short inter pregnancy intervals among pregnant mothers was found to be 49.84% (42.045–57.635) in samples with a size less than 500, while it was 41.161% (27.266–55.056) in samples with a size greater than 500 (Fig. 4, Supplementary Table 2). Moreover, based on the year of publication, the magnitude of short inter pregnancy intervals among pregnant mothers was found to be 42.157% (27.429–56.885) from 2019 up to 2023, while it was 46.9% (34.238–59.562) from studies conducted from 2010 up to 2018 (Fig. 5, Supplementary Table 3).

Fig. 4

Subgroup analysis of short inter pregnancy interval among pregnant mothers in Ethiopia by sample size

Fig. 5

Subgroup analysis of short inter pregnancy interval among pregnant mothers in Ethiopia by publication year

Sensitivity analysis

We conducted a leave-one-out sensitivity analysis to investigate the potential source of heterogeneity in the analysis of the magnitude of short inter pregnancy intervals among pregnant mothers. The results of this analysis demonstrated that our findings were not reliant on a single study. The pooled estimated magnitude of short inter pregnancy intervals among pregnant mothers ranged from 43.2% (95% CI 31.48–54.919) [46] to 46.769% (95% CI 44.98–48.55) after deletion of a single study (Table 2 and Supplementary Fig. 1).

Table 2 A sensitivity analysis of the magnitude of short inter pregnancy interval among pregnant mothers in EthiopiaPublication bias

We conducted a publication bias assessment and observed that the funnel plot displayed a symmetrical distribution, indicating the absence of publication bias. This finding was further supported by the Egger’s regression test, which yielded a P-value of 0.55 (Supplementary Fig. 2 and Supplementary Table 4). Factors Associated with Short Inter pregnancy Interval among Pregnant Mothers Out of the total included studies, 21 studies revealed the factors associated with a short inter pregnancy interval among pregnant mothers (Table 1).

Factors associated with short inter pregnancy intervalNo formal education

Out of the total included studies, eleven studies reported a significant association between no formal education and short inter pregnancy interval among pregnant mothers in Ethiopia (Table 3). Among these studies, the highest risk factor was an (AOR) of 5.28 (95% CI 2.26, 12.36) [28] and lowest risk factor AOR = 1.23 (1.05, 1.45) compared to educated mothers. Regarding the heterogeneity test for no formal education, the Galbraith plot revealed heterogeneity when combining the results of eleven studies. The forest plot displayed the overall estimate of the (AOR) for no formal education as 1.889 (95% CI 1.261–2.517) I2 3.4%, P 0.41.The I-squared (I2) value indicated heterogeneity of 3.42%, and the P-value was 0.41. These findings suggest the presence of heterogeneity in the study results. Furthermore, the I-squared (I2) and P-value also indicated the absence of publication bias (Supplementary Fig. 3).

Table 3 Determinant factors associated with short inter pregnancy interval among pregnant mothers in Ethiopia

Regarding the publication bias for no formal education, the funnel plot analysis indicated an asymmetrical distribution. To identify the potential source of heterogeneity in the analysis of the pooled estimate of no formal education as a risk factor for short inter pregnancy interval, we conducted a leave-one-out sensitivity analysis. The results of this analysis revealed that our findings were not reliant on a single study. The pooled estimate of no formal education varied between 1.889 (95% CI 1.26–2.51) and 2.75 (95% CI 1.811–3.698) after excluding each individual study.

Never used contraceptive methods

Out of the total studies, sixteen studies found a significant association between never using contraceptive methods and short inter pregnancy interval among pregnant mothers. Among these studies, the highest risk factor was an (AOR) of 11.2 (95% CI 5.95, 21.5) [41] and lowest risk factor AOR = 1.56 (1.1, 2.21) [50] compared to their counterparts (Table 3).

Regarding the heterogeneity test for never used contraceptive methods, the Galbraith plot demonstrated heterogeneity when combining the results of sixteen studies. The forest plot displayed the overall estimate of the (AOR) for never used contraceptive methods as 3.38 (95% CI 2.41–4.35), I2 44.9%, P 0.027. The I2 value indicated heterogeneity of 44.9%, and the P-value was also indicated the presence of publication bias (Supplementary Fig. 4). Regarding the publication bias for never used contraceptive methods, the funnel plot analysis revealed an asymmetrical distribution. To identify the potential source of heterogeneity in the analysis of the pooled estimate of never used contraceptive methods as a risk factor for short inter pregnancy interval, a leave-one-out sensitivity analysis was conducted. The results of this analysis showed that the findings were not reliant on a single study.

The pooled estimate of never used contraceptive methods varied between 1.56 (95% CI 0.051–3.069) and 11.2 (95% CI 6.084–16.316) after excluding each individual study. Due to the presence of publication bias, a trim and fill analysis was conducted, resulting in the addition of six studies. The total number of studies included in the analysis became twenty two. The pooled estimate of the Adjusted Odds Ratio (AOR) for never use contraceptive status was found to be 9.38 (95% CI 5.034, 17.4840). The I2 value indicated heterogeneity of 95.5%, and the P-value was 0.036 (Supplementary Fig. 5).

Duration of breastfeeding for lessthan24

Out of the total studies, fifteen studies were significantly associated with short inter pregnancy interval among pregnant mothers in Ethiopia. Among these studies, the highest risk factor was an (AOR) of 66.03 [95% CI 58.32–73.73)] [38] and lowest risk factor AOR = 1.26(0.826, 1.694) [47] compared to those who breastfed for a duration greater than 24 months. When the results of the fifteen studies were combined, the forest plot demonstrated an overall estimate of the (AOR) for duration of breastfeeding less than 24 months among pregnant mothers as 6.69 (95% CI 4.77–8.62) I2 95.5, P 0.00. The I2 value indicated a high level of heterogeneity at 95.5%, Suggesting substantial variability among the study results. The P-value was 0.00, indicating statistical significance. Additionally, both the I2 and P-value indicated the presence of heterogeneity and potential publication bias (Supplementary Fig. 6).

Regarding heterogeneity test, Galbraith plot showed heterogeneity regarding test of publication bias a funnel plot showed an asymmetrical distribution. Egger’s regression test P-value was 0.010, which indicated the presence of publication bias (Supplementary Fig. 7). Trim and fill analysis were done, and eight study were added and the total number of studies become 23 and the pooled estimate of AOR for Duration of breastfeeding for less than 24 was 2.155 [95%CI (1.704–2.725); I2 = 95.5%, P = 0.00] (Supplementary Fig. 8).

Residence

Out of the total studies, five studies demonstrated a significant association between residence and short inter pregnancy interval among pregnant mothers. Among these studies, the highest risk factor was an (AOR) of 6.9 (95% CI 3.32–14.59) [43] and lowest risk factor AOR = 1.47 (0.83, 2.61) [44] compared to those who resided in urban areas. When the results of the five studies were combined, the forest plot displayed an overall estimate of the (AOR) for residence as 2.369 (95% CI 1.048–3.689) I2 36.4%, P 0.185. The I2 value indicated a moderate level of heterogeneity at 35.4%, suggesting some variability among the study results. The P-value for heterogeneity was 0.185, indicating no statistically significant heterogeneity (Supplementary Fig. 9).

Furthermore, the Galbraith plots, used to assess heterogeneity, demonstrated homogeneity among the studies. The funnel plot, used to evaluate publication bias, displayed a symmetrical distribution, indicating the absence of publication bias. Additionally, the Egger's regression test resulted in a P-value of 0.214, further supporting the absence of publication bias. To explore the potential sources of heterogeneity, a leave-one-out sensitivity analysis was performed. The results of this analysis revealed that the findings were not heavily reliant on a single study, suggesting robustness in the pooled estimate of residence as a risk factor for short inter pregnancy interval.

Poor wealth index

Out of the total studies, four studies demonstrated a significant association between a poor wealth index and short birth interval among pregnant mothers. Among these studies, the highest risk factor was an (AOR) of 4.89 (95% CI 1.58–6.39) [15] and lowest risk factor AOR = 1.33 (1.26, 2.22) [51], compared to those who had a good wealth index (Table 3). Combining the results of three studies, the forest plot showed an overall estimate of the (AOR) for a poor wealth index as 2.686 (95% CI 0.916–4.456) I2 86.2, P 0.00. The I2 value indicated a high level of heterogeneity at 86.2%, suggesting substantial variability among the study results. The P-value for heterogeneity was 0.00, indicating statistical significance. Regarding publication bias, the funnel plot displayed an asymmetrical distribution, indicating the potential presence of publication bias. The Egger's regression test resulted in a P-value of 0.00, further supporting the presence of publication bias (Supplementary Fig. 10).

A leave-one-out sensitivity analysis was conducted to identify potential sources of heterogeneity in the analysis of the pooled estimate of a poor wealth index as a risk factor for a short inter pregnancy interval among pregnant mothers. The results of this analysis showed that the findings were not dependent on a single variable, suggesting some robustness in the results. Due to the presence of publication bias, a trim and fill analysis was performed, adding two studies to the analysis, resulting in a total of six studies. The pooled estimate of the AOR for a poor wealth index as a risk factor for a short inter pregnancy interval among pregnant mothers was calculated to be 5.1680 (95% CI 2.136–12.5060). The I2 value reduced to 16.4%, indicating a lower level of heterogeneity, and the P-value was 0.036, indicating statistical significance (Supplementary Fig. 11).

Preceding child being female

In eight studies, a significant association was found between the preceding child being female and a short birth interval among pregnant mothers. Among these studies, the highest risk factor was an AOR of 5.7 (95% CI 3.180–10.3) [15], and the lowest risk factor was an AOR of 1.13 (95% CI 0.74–1.71) [44], suggesting a smaller effect or no significant association compared to the counterpart. Regarding the heterogeneity test and combining the results of eight studies, the forest plot showed an overall estimate of the AOR for the preceding child being female as 1.45 (95% CI 0.88–2.015) I2 16.4%, P 0.301. The I2 value indicated a low level of heterogeneity at 16.4%, suggesting minimal variability among the study results. The P-value for heterogeneity was 0.301, indicating no significant heterogeneity (Supplementary Fig. 12). Regarding the heterogeneity test, the Galbraith plot showed homogeneity, which is consistent with the low level of heterogeneity indicated by the I2 value. Regarding publication bias, the funnel plot displayed a symmetrical distribution, suggesting the absence of publication bias. The Egger's regression test resulted in a P-value of 0.214, further supporting the absence of publication bias. A leave-one-out sensitivity analysis was conducted to identify potential sources of heterogeneity in the analysis of the pooled estimate of residence as a risk factor for a short inter pregnancy interval. The results of this analysis showed that the findings were not dependent on a single study, suggesting some robustness in the results.

Fetal complications

In five studies, a significant association was found between fetal complication and a short inter pregnancy interval among pregnant mothers. Among these studies, the highest risk factor was an AOR of 6.85 (95% CI 3.07–15.3) [54], and the lowest risk factor was an AORof 2.1 (95% CI 1.16–3.82) [45], compared to the counterpart. Regarding the heterogeneity test and combining the results of eight studies, the forest plot showed an overall estimate of the AORfor fetal complications as 3.55 (95% CI 1.986–5.122) I2 0.00, P 0.482. The I2 value indicated no heterogeneity at 0%, suggesting no significant variability among the study results. The P-value for heterogeneity was 0.482, further supporting the absence of of publication bias (Supplementary Fig. 13).

Regarding publication bias, the funnel plot displayed an asymmetrical distribution, suggesting the potential presence of publication bias. The Egger's regression test resulted in a P-value of 0.011, indicating the presence of publication bias. Due to the presence of publication bias, a trim and fill analysis was performed, adding two studies to the analysis, resulting in a total of seven studies. The pooled estimate of the AOR for adverse perinatal outcomes was calculated to be 2.94 (95% CI 1.347–4.540). The I2 value remained at 16.4%, indicating a low level of heterogeneity, and the P-value was 0.286, suggesting no significant heterogeneity (Supplementary Fig. 14).