論文の公開元へTrends and risk factors for infant mortality in the Lao People’s Democratic Republic
概要
【Introduction】
Infant mortality is a major health problem around the world. A high infant mortality rate (IMR) indicates a failure to meet people’s healthcare needs. Lao People’s Democratic Republic (Lao PDR) has the highest IMR in South East Asia. This study aimed to show the infant mortality trends and to identify factors associated with infant mortality.
【Methods】
This was a cross-sectional study using the secondary data of women and their live births from the Lao Social Indicator Survey II (LSIS-II) in 2017. LSIS-II included 25,305 women aged 15–49 from 22,287 households across all 18 provinces. The IMR and neonatal mortality ratio (NMR) for each year were estimated using the data of 53,727 children of the 25,305 women. Factors associated with infant mortality were examined using the data of 2,189 women with live births in the two years before the LSIS-II interview whose last child was a singleton, and whose last living child was aged at least one at the time of the interview or whose last child had died before the interview. Logistic regression was applied to identify risk factors that imposed to infant mortality. In multivariate analysis, the forced- entry method (Model 1), the forward stepwise selection (Model 2), and the backward stepwise selection (Model 3) were applied.
【Results】
1. Estimation of the IMR and NMR
The IMR (per 1,000 live births) was 191 in 1978–1987, decreasing to 39 in 2017 (Fig. 1).
The NMR (per 1,000 live births) rapidly decreased from 117 in 1978–1987 to 43 in 1989 and then slowly declined to 18 in 2017.
2. Mortality of children born in the 2 years before LSIS-II
The overall survival rate of the 5,013 children was 95.5% in the first 2 years of life (Fig. 2). The survival rate was 97.8% at 1 month of age and gradually decreased to 96.0% at 1 year.
3. Comparison of the characteristics of women according to their last child’s infant mortality
In all 2,189 women, women whose last child had higher infant mortality were younger than 18 years, living in rural areas, the Mon-Khmer ethnic group, low education levels, poor households, husbands younger than 18 years, and the first marriage younger than 18 years (Table 1). There were nine obstetrical factors that were associated with high infant mortality (Table 2). Male babies and small-sized babies at birth had 1.48- and 3.77-times higher infant mortalities than the others, respectively. Women who approved of violence toward a wife who refused sex with her husband and who burned food showed higher infant mortality (Table 3).
In 1,950 women whose last children were average or large at birth, aged 15–17, residing in rural areas, the Mon-Khmer ethno-linguistic group, no or early childhood education, the poorest wealth index, and the first marriage younger than 18 years old were associated with high infant mortality (Table 1). Women who were pregnant at the time of the interview, had anemia, fewer than four antenatal care (ANC) visits, ANC providers other than doctors, no iron supplementation or tetanus immunization during pregnancy, home births, auxiliary nurses or others as birth attendants, and male babies had higher infant mortalities (Tables 2−3). Women who accepted husbands’ violence toward their wives when she goes out without informing him, refuses sex with him, and burns food showed higher infant mortality (Table 3).
4. Multivariate logistic analysis on factors associated with high infant mortality
Forward-selection stepwise (Model 2) and backward-selection stepwise (Model 3) regression were applied for variable selection, while the forced-entry method (Model 1) used all variables for adjustment. The results of analyses were compared in the three models. Factors associated with high infant mortality in all three models were (1) having auxiliary nurses as birth attendants compared to doctors, male infants, and small infants in all women (Table 4); and (2) being pregnant at the time of interview, 1–3 ANC visits compared to four or more, having auxiliary nurses as birth attendants compared to doctors, having male infants, and having a postnatal baby check in women whose babies were average or large at birth (Table 5).
【Discussion】
The estimated IMR and NMR gradually decreased from 1978 to 2017. However, the IMR still remains high and a decrease of the difference between the IMR and NMR stopped after 2009. This may be attributable to a thiamine deficiency, which is associated with sudden infant death syndrome and may contribute to high infant mortality. To prevent thiamine deficiency, nutrition education to pregnant and childbearing women should be provided.
In all women, auxiliary nurses as birth attendants compared to doctors, male infants and small size at birth compared to average were significantly associated with high infant mortality. Males have a biologically higher risk of mortality and morbidity than females throughout life. Auxiliary nurses are medical professionals established in 1975 to address the nursing shortage after the Laotian Civil War. The education for auxiliary nurses was shorter (3–12 months) than nurses (at least 2 years). To reduce infant mortality, currently employed auxiliary nurses should be upgraded to at least mid-level nurses through additional education or training.
When the data of women whose infants were average or large size at birth were analyzed, five factors were associated with high infant mortality in all three models. A short interpregnancy interval increases the risk for preterm births; small for gestational age; and adverse fetal and infant outcomes. These results suggest that short interpregnancy intervals could be causing higher IMRs in Lao PDR by negatively affecting maternal health conditions. Increasing availability of contraception would be an important intervention to increase the interpregnancy interval.
The current results suggest that four ANC visits or more are needed to improve the IMR. The Lao government set the target of the coverage of at least one visit and four visits of ANC as 90% and 75%, respectively, by 2020. The ANC coverage improved from 37.5% in 2006 to 54.2% in 2012 and 79.1% in 2017 (this study). Moreover, the percentage of women who had postnatal baby checks was only 13.5%, which was much lower than the ANC coverage. Having to travel long distances to hospitals, road conditions, and lack of transportation are barriers to accessing health services in Lao PDR. These factors suggest that Lao women may only take their babies to the checks when they are moderately or severely ill.
This study had some limitations. First, recall bias might have occurred, as the women reported on their behaviors and experiences in the previous 2 years. Second, babies’ size at birth was used rather than birth weight. Finally, women whose data were missing were excluded; however, these women might have experienced greater infant mortality.
【Conclusion】
In Lao PDR, the estimated IMR and NMR decreased from 1978 to 2017, and the difference between the IMR and NMR did not change after 2009. Auxiliary nurses as birth attendants compared to doctors, male babies, small-sized babies at birth, pregnancy at the time of the interview, 1–3 ANC visits compared to four visits, and having postnatal baby checks were associated with high IMR. The Ministry of Health should strengthen maternal and child health. Family planning and health education for all citizens also need to be strengthened.
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