Association between Breastfeeding and Child Stunting among Adolescent Mothers

Introduction: Child stunting is one of the global public health problems and breastfeeding is one of the modifiable maternal factors protecting against child stunting. The current study aims to determine the prevalence of breastfeeding and its association with child stunting among adolescent mothers. Methods: A cross-sectional study was conducted in Phra Nakhon Si Ayutthaya province. Using multi-stage stratified sampling method, 250 participants were recruited. Data were collected using structured interview questionnaires in 6 districts from August 2016 to March 2017. Descriptive and analytic statistics were used to analyze data. Results: 16.4% of children were stunted and 22.4% were breastfed for ≥6 months. Univariable logistic regression disclosed significantly associated factors of stunting included age at delivery, educational level, family members, weight gain during pregnancy, birth weight, complete immunization, recent illness, breast feeding and complementary feeding (p-value < 0.05). After adjusting multivariable logistic regression analysis for potential confounders, babies breastfed <4 months were 1.83 times at risk compared with those breastfed ≥6 months (OR=1.83, 95%CI=0.41-8.30) but without significance. Conclusion: Efforts to reduce child stunting should include surveillance systems of stunting which should be conducted accompanied by providing perspectives on maternal and child health care, implementing health literacy regarding breastfeeding among adolescent mothers and prevention programs to reduce and prevent child stunting.


Introduction
Stunting is the most prevalent form of child under-nutrition and one of the global health problems, a deficit of height to age relation, and it is responsible for delayed development including impaired cognitive function and increased susceptibility to infectious diseases among children. The World Health Assembly is dedicated to supporting the achievement of the Global Nutrition Targets 2025 to reduce by 40% the number of children under five years who are stunted [1]. In 2012 globally, approximately 162 million children under five were stunted [2]. Global prevalence of stunting in 2019 increased 21.4% [3]. In developing countries, approximately 40% of children under five are stunted [1], over 200 million young children. Stunting rates among children under five years are unconscionably high in Africa and South Asia countries, because children's height or length can develop when they receive adequate nutrition since the beginning of life [4][5][6]. In Thailand, 16.3% of children under 5 years were stunted, and 5.9% present severe stunting at risk of low intelligence [7]. Nutrition is one of the key factors to achieve adequate child growth and development [8]. In particular, breastfeeding has been associated with maternal and child health benefits [9]. The first 1,000 days of life are a critical period to intervene and prevent stunting in order to achieve short and long-term healthy growth [10]. One of the risk groups are adolescent mothers. They were associated with stunting among children, because of being young and lack of maturity and nutritional knowledge to take care of their child. In addition, many had unplanned pregnancy, and might not have been aware of food consumption since becoming pregnant [11][12]. Moreover, trends of stunting among children under 6 months were higher but lower when they aged up to 36 months [7]. Hence, the present study aimed to determine the prevalence of breastfeeding and its association with stunting among children 6 to 36 months of adolescent mothers in Phra Nakhon Si Ayutthaya Province. The author selected Phra Nakhon Si Ayutthaya province as the area of study because of its characteristics as a proxy of central provinces of Thailand with an area of about 2,557 km 2 . It lies around 70 km north of Bangkok, the capital of Thailand containing a population of 817,441 and density 320/km 2 in 2018 [13][14]. In addition, average adolescent birth rate (56.2/1,000) in Phra Nakhon Si Ayutthaya Province was higher than that of provinces under the Regional Heath Office 4 (51.5/1,000) and Thailand (51.2/1,000) in 2013 [15].

Study design and setting
The analytical cross-sectional study was conducted from August 2016 to March 2017 to explore prevalence of stunting and determine the association between breastfeeding and stunting occurrence among children aged 6-36 months of adolescent mothers in Phra Nakhon Si Ayutthaya Province, Thailand.

Sample size and sampling technique
The sample size was calculated using a formula with specified absolute precision [16] according to the following assumptions: 10.48% of stunting among children (P) [17], with 95% confidence interval and 5% specified absolute precision (d). As a multistage sampling technique was employed to identify study subjects, a design effect of 1.5 was used. The calculated sample size was at least 218. Also, approximately 10% was added to adjust for nonresponses. Thus, the final sample size was at least 250.

Measures
Information was obtained by interviewing the study subjects by the researcher and trained research assistants. The questionnaire comprised demographic factors of maternal and child, factors of breastfeeding and stunting. Stunting was evaluated using the definition of WHO [18].

Variable Definitions
Child Stunting is a chronic restriction of a child's potential growth and development. A child aged 0 to 59 months is classified as stunted when her/his height for age falls below the -2 standard deviations from the median height for age determined by the WHO Child Growth Standards 2006 [8,[18][19]. Adolescent Mother means the mother whose age at delivery was less than 20 years.
Exclusive Breastfeeding is defined as the period after birth during which the infant was fed only breast milk (with the exception ordered medicines and vitamins by health professionals) one day (24 hrs) before the survey was conducted [20][21].
Complementary Feeding is defined as the period the infant was fed breast milk with addition of liquid foods like cow milk and formula milk and soft foods like mashed potatoes/meat, porridge, egg or butter one day (24 hrs) before the survey was conducted [22].

Ethical Issues
This study was reviewed and approved by the Ethics Committee for Research in Human Subjects of the Faculty of Public Health, Mahidol University (Committee's reference number: MUPH 2016-096 on 7 th July 2016) and agreed with the Declaration of Helsinki, All participants participated in this study on a voluntary basis. Informed consent to participate in the study was obtained from participants after informing them the details of study. The participant's responses were strictly confidential and were unused for any other purpose. The decision to participate or not did not rely on any other person apart from the participants themselves. Participants' names were unidentified in questionnaires, confidentiality was conducted throughout the study using anonymous techniques and the results were analyzed as a whole group.

Statistical Analysis
The data were analyzed using the statistical package. Categorical variables were given as frequency and percent, crude odds ratio (OR c ), 95% CI of OR and p-value. Moreover, numerical variables were expressed as mean, median, minimum and maximum, standard deviation. Univariate analysis was performed using the univariable logistic regression to differentiate proportional exposures between stunted and normal children for categorical variables. Adjusted odds ratio (OR adj ) and 95% CI of OR were calculated from the multivariable logistic regression to examine associations between breastfeeding and stunting occurrence, adjusted for potential confounders.
All statistical analyses were performed using two-sided tests and a p-value of <0.05 was judged to be statistically significant.
Of 250 children with adolescent mothers, prevalence of stunting was 16.4%. Using univariable logistic regression, associated demographic factors of mothers and children included age at delivery, education, family members, weight gain, birth weight, immunization, recent illness, breastfeeding and complementary feeding (p<0.05), as shown in Table 3. Multivariable logistic regression, association between breastfeeding, complementary feeding and stunting among young children (adjusted for potential confounders), babies with breastfeeding <4 months were 1.83 times at risk compared with those breastfeeding ≥6 months (OR=1.83, 95%CI=0.41-8.30) but without significance, as shown in Table 4. Comparing height for age with Z score and standard deviation revealed significant stunting as shown in Table 5. ORc = crude odds ratio, ORadj = adjusted odds ratio for age at delivery, educational level, family members, weight gain during pregnancy, birth weight, complete immunization, recent illness history and complementary feeding Table 5. Number and percent of height for age graph of growth status

Discussion
The findings showed that the prevalence of child stunting was approximately 16.4% higher than related studies conducted in Thailand [17,23]. Evidence from related studies on stunting showed the prevalence of stunting was approximately 10.5% [17,23]. Our investigation indicated a serious health problem among teenage mothers, possibly stemming from unwanted pregnancy, poverty, low education and other unsuitable maternal socio-economic factors [24]. Several studies have shown that adolescent mothers were too young, too immature and lacked sufficient nutritional knowledge to take appropriate care of their child. In addition, teenage mothers with unplanned pregnancy might be unaware of food consumption needed to support embryo growth and development. This would create a continuing effect on her nutritional status throughout the pregnancy. Their nutritional status during the time they became pregnant was also an important factor that influenced the health of the fetus, as well as long term health of the infant [11][12].
The study indicated only 22.4% practiced predominant breastfeeding over 6 months, and 32.4% breastfed exclusively 4-5.9 months, while 45.2% breastfed their babies less than 4 months. This study also found that exclusive breastfeeding <4 months had a positive association with stunting but without significance (p>0.05). However, exclusive breastfeeding times were associated with underweight status among children because giving any other liquid or food apart from breast milk, before 4 months, was associated with increased risk of gastro-intestinal disease, resulting in growth retardation, micronutrient deficiencies and vulnerability towards various infectious diseases within the first 2 years of life 490 Association between Breastfeeding and Child Stunting among Adolescent Mothers [25][26]. Regarding the duration of complementary feeding, mostly over 6 months (51.6%), the result showed no significant association with stunting. Similarly, related studies showed the pattern of growth and development was unrelated to the duration of breastfeeding [27][28]. In contrast, a recent study of Syeda et al. showed a positive relationship between breastfeeding in the second and third year of life with stunting [29]. Several studies showed breastfeeding's benefits in reduction of child under-nutrition [30][31][32][33]. Breastfeeding was beneficial compared with formula feeding among infants according to Dimnjakovic [34]. The WHO recommends among health infants introducing complementary feeding should be delayed until 6 months of exclusive breastfeeding to confer several benefits to the infant and mother [1]. Early feeding to solid foods, early cessation of breastfeeding and increased consumption of fatty or sugary foods at one year of age were proven risk factors for infection. The WHO and United Nations Children's Fund recommend that breastfeeding a child up to 2 years of age is essential for proper growth and development [1].

Study Limitations
This study encountered a few limitations that needed to be addressed. First, the cross-sectional survey reduced the ability to make direct causal inferences, we couldn't rule out reverse causation or assess the temporal relationship of some factors preceding child stunting. Second, these data apply only to those teenage mothers in a rural area; therefore, they could not represent all teenage mothers. Third, this study used only height for age for stunting and might not include all stunting. Finally, all data were collected from teenage mothers. Most had mental health problems, such as depression and stress disorder. In addition teenage mothers were also more likely to reside in communities and families that were socially and economically disadvantaged. These circumstances could have adversely affected outcomes for their children.

Conclusions
Our results suggest that efforts to prevent and reduce child stunting should include the surveillance system of stunting and campaign of healthy diet and basic techniques for healthy lifestyles among risk groups should be established along with knowledge sharing programs about associated factors of stunting among adolescent mothers to minimize and reduce risks of child stunting.