@2024 Afarand., IRAN

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ISSN: 2252-0805    The Horizon of Medical Sciences 2015;21(2):141-146

Background
Factors such as increase in maternal age, infertility treatment techniques, high rates of cesarean delivery and management of all the complicated pregnancy can lead to premature birth [1]. … [2-6] Premature birth is a multifactorial condition [7] such as social, psychological, biological and genetic factors can be mentioned [8].
Previous Studies
Several factors such as premature rupture of membranes, uterine and placental problems, preeclampsia, records of abortion or fetal death, hypertension pregnancy and vaginal infections have mentioned as factors associated with prematurity [9]. … [10] Demographic and social factors and lifestyle, such as maternal education and poverty [11], dietary habits [12] and factors such as mother's smoking, body mass index, racial inequality and access to health care are factors that can predispose to preterm birth [5]. Social and psychological effects of domestic violence and abuse during pregnancy are accompanied with the increase in the risk of miscarriage, prematurity, low birth weight, maternal and fetal mortality, uterine rupture, hemorrhage, etc. [13]. Different available methods of contraception have been recognized as an effective risk factor for low birth age [14]. … [15]
Aim(s)
This study aimed to identify modifiable risk factors associated with preterm birth in Gonabad (Iran).
Research type
This is a retrospective case-control study.
Research society, place and time
Premature infants in the neonatal department of Gonabad 22nd of Bahman Hospital were studied in 2012-2013.
Sampling method and number
After a pilot study, sample size was determined using a formula to compare proportions. 73 infants were chosen by convenience sampling method as a case group and 161 normal birth weight infants were randomly selected as a control group. Inclusion criteria included: consent to participate in the research and preterm infants (born before 37 weeks) for case group, and mature infants for control group, which was recorded in their medical records. After choosing each case baby, mature babies (n=3×number of the case babies), who had the same age and sex and were from the health center, were randomly chosen.
Used devices&materials
Variables included maternal age, paternal age, parents' education and occupation, residence, living conditions, income, history of preterm birth, physical violence, immigration status and participation in the prenatal classes. The research tools included a demographic characteristics form, obstetric data and information on the infants. The validity of the questionnaire was determined by content validity and its reliability was determined using Test-retest. Data were analyzed using SPSS 18. To compare qualitative variables between groups, Chi-square test, Fisher test, and Kendall Tau were used. To compare the quantitative variables in two groups, such as age, , and to assess the effect of variables on the premature birth, Independent T-test and Logistic Regression were used.
Findings by Text
The average age of mothers of premature infants was 29/66 ± 6/26 years and the average age of mothers of mature infants was 28.88± 5.76 years. Two groups did not have significant difference in terms of mother’s age, father’s age, mother’s occupation, father’s education, living conditions and physical violence. However, there was a significant difference in preterm and mature infants groups in mother’s education level, and the mothers of mature infants had higher level of education. In addition, there was a statistical significant difference in father’s occupation (Table 1). Two groups had significant differences in the record of premature birth and attending in prenatal education sessions. The groups had a significant difference in total income, and control group had totally a higher income level. A significant difference was observed between the groups in unwanted pregnancies, and in premature newborns group, mothers had a higher percentage of unwanted pregnancies (Table 2). 8 mothers (38.1%) of premature infants and 13 (54.2%) mothers of mature infants stated that the most common cause of unwanted pregnancy was unawareness of different contraception methods. In addition, in case group, 4 mothers (19.0%) mentioned the lack of access to various methods of contraception as the cause of unwanted pregnancy, and 2 (9.5%) mothers did not believe in these methods and their effectiveness; in control group, 4 mothers (16.7%) mentioned lack of belief in these methods as the cause of unwanted pregnancy. However, there was no significant difference in the cause of unwanted pregnancies between two groups. In residence location, number of children, migration from rural to urban place and from city to city and type of delivery, there were significant differences between the groups (Table 2). Logistic Regression analysis showed that the risk of newborn babies in a city was 2.5 times more than of the village. The possibility of mature newborn infants in those who participated in prenatal classes is nearly 3 times more than those who do not participated in the classes, and the more the premature birth history, the less the chance of mature newborn infants’ birth was (up to 93%). In addition, the higher the income level, the less the chance of mature infants’ birth was (up to 92%).
Main comparison to the similar studies
Two groups had significant differences in mother’s education, father’s occupation, number of children, income, residence location, immigration status, pregnancy sessions, unwanted pregnancy, type of birth and history of premature birth. And after logistic regression, only 4 variables including low-to-moderate income level, residence location, pregnancy sessions and a history of premature birth were the predictors of premature birth. In total, those in control group had a higher education level. These results were incompatible with some studies [16, 17]. Women with low socioeconomic status and low education levels are at twice risk of preterm delivery [15]. No significant difference was observed in maternal age in mature and preterm infants groups. Under 18 years women firstly pregnant have a higher chance of premature birth [18], and the prevalence of premature infants of mothers under 20 years old has been reported 8/8% , and in women over 35 years old, it has been reported 6.7% [19] that are different from the results of the present study. Premature birth was associated with low to moderate incomes. Relative risk of low birth weight in mothers who deliver a child in a period of economic collapse is 1.24, but this economic collapse has not led to any change in the risk of preterm neonates [20] that are not consistent with the current study. The risk of premature birth increases with less participation in the pregnancy classes. Chance of preterm birth in those, who have had less than 4 prenatal care sessions, have been 4.15 compared to mothers who received 9 care sessions [17]. In premature group, the ratio of mothers receiving prenatal care shows a less percentage [5, 21, 22]. Mothers with registered cares are less likely to have a premature birth [15]. In both groups there was no significant difference in the residence location, and the chance for term birth in the city is higher than the village. Women, who live in the city, are less likely to have a premature birth [15] that is in accordance with the results of the present study. War immigrants in Sweden have been at an increasing risk of preterm birth, especially in the first year and the relative risk in the first year has been 1.39 [23]. In case group, 31.5%, and in control group, 14.9 % had unwanted pregnancies, and unwanted pregnancies in both groups were significantly different. The chances of premature birth in unwanted pregnancies is 2.1 times more than premature birth in the wanted pregnancy[17] which is consistent with the present study. A higher percentage of mothers with premature infants had a history of preterm birth and the chance of preterm infant birth increased with an increase in the history of preterm infants, which is in accordance with the results of other studies [8, 24, 25]. The most important risk factor for preterm birth is a premature birth with a relative risk equal to 12.7 [8]. Preterm birth has been associated with a history of preterm birth [25]. 93.2% of the mothers of premature infants and 85.7 % of mothers of term infants are housewives and there is no significant difference between mothers’ occupation in both groups, which is in accordance with the results of other study [13].
Suggestions
There should be cautious in generalization and comparison of the results with other studies.
Limitations
Probably time to recall is effective. Some factors associated with premature birth have not been considered. Sampling has been carried out based on availability.
Conclusions
Among the modifiable factors, place of residence, participation in prenatal classes, a history of premature birth and low to average income levels are associated with the risk of premature birth.
Acknowledgments
The Deputy for Research and Technology, Student Research Committee and all participating mothers are appreciated.
Conflict of interest
Non-declared
Ethical Permissions
This study has been approved by Gonabad University of Medical Sciences.
Funding Sources
This study has been conducted by the financial support of Research and Technology Department of Gonabad University of Medical Sciences.

TABLES and CHARTS

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