Tehran Survey of Potential Risk Factors for Multiple Births

Iranian school-aged twin registry: preliminary reports and project progress

BACKGROUND

National Persian school-aged twin registry was established to provide a platform for twin studies. In this report, we describe defining registry characteristics, database design, and preliminary results regarding gathered data in the first phase of the registry program.

METHOD

Through focus group discussions, the required data elements to design the database and data collection process were defined. First, a list of twins in school-aged groups was retrieved from the electronic database of the Ministry of Education. Tehran schools were selected for the first phase of our registry. Standard "Pea-in-Pods" questionnaire and twins' similarity questionnaires were filled out by the parents themselves in addition to demographic information. Data were analyzed using SPSS v.22.

RESULTS

The first national school-aged twin registry was established in 2018. Firstly, the required data sets and data collection process were defined using focus group discussions. At the country level, the initial information on 189,738 students was retrieved from the national database of the Ministry of Education. They were born between 2003 and 2017, of which 94,997 are boys (50.1%) and 94,741 are girls (49.9%). Of them, a total of 5,642 pairs of school-aged twins participated in the first phase of our program. Our sample size comprised 9772 twins, 906 triples, and 92 quadruplets. The analysis of the zygosity questionnaire showed that 14% of twin pairs were identified as monozygotic twins.

CONCLUSION

Recruiting school-aged twins through school health assistants leads to high enrollment and decreasing costs for the twin registry. The study showed a high rate of dizygotic twins that need to be verified by twin bio-sample in the next phase of studies.

Socioeconomic inequality of unintended pregnancy in the Iranian population: a decomposition approach

BACKGROUND

There are several studies regarding the predictors or risk factors of unintended pregnancy, but only a small number of studies have been carried out concerning the socio-economic factors influencing the unintended pregnancy rate. This study aimed to determine the socioeconomic inequality of unintended pregnancy in Tehran, Iran, as a developing country.

METHODS

In this hospital based cross-sectional study, 5152 deliveries from 103 hospitals in Tehran (the capital of Iran) were included in the analysis in July 2015. Socioeconomic status (SES) was measured through an asset-based method and principal component analysis was carried out to calculate the household SES. The concentration index and curve was used to measure SES inequality in unintended pregnancy, and then decomposed into its determinants. The data was analyzed by statistical Stata software.

RESULTS

The Wagstaff normalized concentration index of unintended pregnancy (- 0.108 (95% Confidence Interval (CI) = - 0.119 ~ - 0.054)) endorses that unintended pregnancy is more concentrated among poorer mothers. The results showed that SES accounted for 27% of unintended pregnancy inequality, followed by the mother's nationality (19%), father's age (16%), mother's age (10%), father's education level (7%) and Body Mass Index (BMI) groups (5%).

CONCLUSION

Unintended pregnancy is unequally distributed among Iranian women and is more concentrated among poor women. Economic status had the most positive contribution, explaining 27% of inequality in unintended pregnancy.