This project seeks to contribute to the current literature of son preference and sex imbalance in Vietnam and other developing countries by extending the measure of “son preference” to birth interval, number of children and probability of using contraceptive methods.

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To: Fulbright U.S- Asean Visiting scholar program
From: Ms. To Thuy Hanh
Statistician
Social and Environmental Statistics Department, Viet Nam General
Statistics Office
Research Proposal
Title: Son preference and fertility behavior evidence from Viet Nam
1. Abstract:
Viet Nam is conducting programs, strategies on gender equality in every section such
as women empowerment, or improving capacity of women on accessing resources.
One of inequality issues that we can see very clearly is Son preference among fertility
behaviors. My country is facing high sex imbalance in recent years. The sex ratio at
birth equals 112.3 percent in 2014, which is much higher all other countries in the
region. High sex imbalance causes serious economic and social problems. Sex
discrimination, in which boys is overvalued than girls, determine the fertilize behavior of
each families. This study aims to investigate the “son preference” issue among
households in Vietnam by looking at the factors which may influent the birth’s choice of
women.
This thesis seeks to contribute to the current literature of son preference and sex
imbalance in Vietnam and other developing countries by extending the measure of “son
preference” to birth interval, number of children and probability of using contraceptive
methods. These extensions allow us to explore a broader aspect of son preference.
The results provide useful suggestions to policy makers in Vietnam and other
developing countries. Specifically, it investigates a variety of indicators relating to
fertilize decisions, which provides a clearer picture of the son preference issue. In
addition, I control for a broader factors which may influence the choice of the sex of
children and fertilize decisions. By focusing the factors that affect the son preference,
policy makers can provide suitable policy to reduce the sex imbalance.
2. Brief summary of literature review:
Birth interval and number of children are the two main indicators that reflect fertility
decision. Women may expand or narrow the length of birth interval which reflect their
attitude about gender discrimination. Bio-behaviors is also reflected by the use of
contraceptive methods to postpone or delay pregnancy. The difference between the
probability of using contraception among women who had and have not had sons is
also a signal of sex selection.

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Haughton and Haughton (1995) propose a measure of the length of birth interval which
is the distance between one birth and the next. Determinants of the length of birth are
grouped into 3 categories of variables, including maternal variables, household
variables and geographic effects. Following the McClelland’s (1983) method, they
develop a utility function of son and daughter where children are consider as inferior
goods. They extend a numerous factors, which were assumed to influent fertility
behavior. These variables are considered as control factors and are divided into three
groups (i) maternal characters included educational level, dummy variable on reading
capacity, working status, marital status, age at birth/married; (ii) household information
such as sex of household head, expenditure per capita per year, husband education.
(iii) The last group is geographic character, which covered dummy variable of area
(urban and rural), regions. The main findings were son preference in Vietnam is a
matter of household behavior, and each family desired to have one boy instead of many
boys to maintain the structure of the family.
Guilmoto (2012) analyses son preference, sex selection and kinship in Viet Nam using
data from 15 percent sample of the 2009 Census. The change in birth masculinity is
investigated through social and geographical factors. Guilmoto (2012) also study the
role of factors related to sex selection, and the differences between regions in sharing
male births and find a link between total fertility rate and sex ratio at birth. Guilmoto
(2012) reports that birth masculinity is more serve in provinces of Red River Delta than
other regions, it is as twice as higher than provinces from Central Highland to the South.
A multivariable model of correlates of birth masculinity was built, with number of
observations is 63 provinces.
Rohni and Anju, (2006) investigate 50,136 ever married women find various factors
explaining son preference in rural area of India. These factors can be divided into three
levels; individual level includes, household level, community factors. They also show
that the difference could not be explained directly by the wealth of household or
community economic development. However, it significantly influenced by women’s
education and media exposure. Women with higher level of education are less
preference to sons to daughter than women with lower level of education. Similarly, the
more exposure to media and entertainment services the weaker son preference.
Dahl and Moretti (2008) show child gender influent marital status, structure of family and
fertility over families in America. Their findings conclude that first born daughter has
small chance to live with father than first born son. It analyses the relationship between
first child sex and fertility, and number of children is selected to represent fertility. First
born son is used as control factors in all models, authors interaction term between first
born sex and with other control factors, such as first child age, ultrasound. Model’s
results show that families have more children if first born child is a girl, then American
parents prefer sons than daughters.

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3. Research objective & research questions:
The main objective of this study is to examine whether the gender of children can affect
the fertility behaviors of families in Vietnam. More specifically, it aims to answers the
follow research questions:
- To what extent does the gender of the first-born children can affect the number of
siblings?
- To what extent does the gender of the first-born children can affect the birth
spacing between children?
- To what extent does the gender of the first-born children can affect the using of
contraceptive method currently (probability of using Contraceptive method)?
- Does the effect of the first-born gender on fertility, birth spacing and using of
contraceptive method vary across different types of families with different
education, regions, and income level?
4. Data and methodology:
4.1. Data:
I use data from the Multi indicators cluster survey in round 5 (MICS 2014), it was a
survey which applied face-to-face interview to collect data. The MICS 2014 interviewed
9,827 women at aged 15-49 years in 9,979 households over country in 2014. The MISC
2014 sample was representative to households in the country and region. The sample
comprises 4,200 women in urban area and 5,627 women in rural area. Percentage of
women in each age group is quite similar, around 14 percent or approximate 1400
women per age groups. Ethnic minority women account for 14 percent in the sample
compare to 86 percent of Kinh/Hoa women. Specifically, MICS 2014 data can identify
bio-children of women by Birth History module, which collects all birth (deaths and live
births) during the women’s fertility life. In addition, the MICS 2014 contain three groups
of questionnaires to collect information on the household, women and children’s
characteristics. So it provides information to describe a whole picture of women’s
situation.
In order to examine the change over time, MICS is suitable data source because it is
periodical survey which conducted every 4-5 years. MICS3 was conducted in 2006 and
MICS4 in 2011. MICS survey is a standard survey, therefore information collected in
third, fourth and fifth round are similar and can be combine.
4.2. Methodology:
a. Evaluation of sibling through birth interval, number of children or probability of
currently contraceptive method
Sex discrimination is expressed by the relationship of birth interval or number of child or
contraceptive method with sex of first child. Regression model is developed to analyze

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the relationship between first child sex on birth interval or number of children as
dependent variable. First child sex is random and dummy variable with 2 values (1 and
0). Beside of first child sex factor, this thesis refers Haughton and Haughton (1995) to
add more control factors such as living area, living regions, household characters and
women’s characters. In addition, interaction term is created by first child sex and other
control variables to examine the combined impact on output variables (Dahl and Moretti,
2008). The linear form of model is:
While : Sex of first child with 2 values (1 for male and 0 for female)
: Control variables
: Birth interval with values in range from 0 – 17; or number of children of each woman;
or probability of currently contraceptive method using.
Poisson regression model is applied because dependent variable is nonnegative integer
count variable. It is transformation of linear regression model and is written as:
b. The first child sex and birth interval
First model uses first born son as only one control factor:
Second model uses first born son and other factor as control factors:
Third model interacts first born son with other factor one by one to examine interacted
impact; model below is an example of interaction between first born son and first born
age variable.
Xi: Control variables include household characteristics (living area and ethnicity) and
women characteristics (age and education level)
bi: birth interval counted by years
fson : first born child is son
fage : age of first child
urban: living area includes urban and rural
region: 6 regions
ethnicity: is ethnicity of household head
then

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wealth: wealth index quintiles include 5 quintiles from poorest to richest group
wage: age of woman
medu: woman (or mother ) education is highest grade that women attended
c. The first child sex on number of children
d. Contraceptive method and sex of first child
Variable y is aggregated into binary values, 0 if woman currently is not using
contraceptive method and 1 if vice versa. Logistic model also developed for other
control factors and interaction variables as Poisson model for birth interval.
5. Ethical considerations:
This research uses MICS dataset therefore it is not harmful ethical research. MICS is a
global survey and it was set up with a list of ethnical principals, one of them is
confidential information. It means all information collected from household, women and
children are only used for research with no identification. Dataset is not included
identification’s information so it is completely to be used for research.
I work in GSO and participated in MICS in round 4 and 5, therefore I have a permission
for using MICS dataset to do research and commit my research will be share with my
office and not for commercial purpose.
6. Conclusion:
My research proves that son preference is available on fertility behavior of each couple
and to identify factors which are considered as determinants of birth decisions. The
research expected to show 2 points; firstly women are set as core factor on eradicating
son preference. Secondly solutions for sex imbalance should be suggested by studying
control factors on fertility.
I expect supports for improving methodology, instead of using one output indicator,
research can test cases by using different indicators separately which reflect woman’s
fertility. I think this method is efficient for limited data, to support examine previous
assumption and give a firm conclusion. Another support is to disseminate the research
result to national agencies, politicians who work on reproductive section, gender
equality. It can be a new message, a new view on son preference as well as suggest
ideals to overcome and eradicate sex imbalance.