The data were collected through a population-based sample in a cross-sectional analytical descriptive study at Health and Medical centers of Hamadan city in the west of Iran from September 2015 to May 2016. The sample was drawn through a cluster sampling method. This survey compared differences of perception of pregnancy risk of nulliparous pregnant women in two age groups. We selected 240 nulliparous pregnant women aged 15 to 35 years by a cross-sectional sampling method within third trimester of pregnancy and were divided them into two age groups, 18 to 35 years aged (160 women) and under 18 year (80 women). The inclusion criteria were singleton pregnancy, speaking, reading, and writing in Persian and presented and a lack of apparent medical or obstetric risk. Women were recruited via prenatal classes and prenatal care departments. Usually, very young (<18-year-old) women have been classified as high-risk group for child bearing [14,15] and women aged 18–35 years of age represented the reference group.

The study was approved by the Ethical Committee of the Research Council of Tehran University of Medical Sciences (Number: 9121151004), Tehran, Iran. The aims and importance of the study were adequately explained to the participants. Study participants signed informed consent forms and were assured of their right to refuse to participate.

The questionnaire gathered background information, including socio demographic characteristics, pregnancy history, pregnancy risk perception and pregnancy related anxiety. The study participants were given a self administered questionnaire.

The nine, visual scale of the Pregnancy Risk Perception Questionnaire (PRPQ) used to measure the perception of pregnancy risk. This questionnaire consists of two sub scales that involves, five questions about risk for baby and four questions about risk for self (mother), yielding a score ranging from 0 to 100. This questionnaire consists of two sub scales, mean scores for each subscale and total scale was calculated, higher scores demonstrate higher levels of perceived risk. Reliability processes indicated that the PRPQ with Cronbach’s alpha 0.87 for the total scale is reliable [16].

After gaining permission to translate Pregnancy Risk Perception Questionnaire into Persian language, forward–backward translation method was used to translation by two experts, after combining two independent translations, the final Persian version was translated back into English by two experts. Finally, the English version was compared with the original.

Women’s fears about their health, their baby’s health and childbirth were assessed by the pregnancy related anxiety scale, this scale consists of 10 items in 4 scales, from 1 (never or not at all) to 4 (a lot of the time or very much). A higher score indicates a higher level of pregnancy-related anxiety [17].

All statistical analysis were performed with SPSS version 20.0, at the 5% significance level. The independent t-test was performed to examine the differences between means of perception of pregnancy risk and pregnancy-related anxiety level in the two groups. The Chi-square test or the Fisher’s-Exact test were used to examine the differences in categorical variables.

A total of 240 nulliparous women (160 women aged 18 to 35 years as a normal age group and 80 women < 18 years as a high risk age group) were selected during pregnancy according to the inclusion criteria. The mean (SD) age range of high-risk group and reference group were 16.61 (1.06) and 26.25 (4.54), respectively. The mean (SD) of gestational age of high risk and reference groups were 31.31 (3.29) and 31.25 (4.35), respectively. Family history and current pregnancy situation were compared between the two groups [Table/Fig-1].

Mean score of perception of pregnancy risk was different in various age groups of pregnant women [Table/Fig-2]. Differences in pregnancy risk perception in high-risk and reference groups were tested with the independent t-test. Women aged < 18 years had a statistically significant higher level of total perception of pregnancy risk and risk perception of herself (risk for the mother) scores than those of women aged 18 to 35 years [Table/Fig-3]. The perception of having a risk for herself during pregnancy, the risk of unborn baby, the risk of haemorrhaging, the risk of having a cesarean section, the risk of dying and the risk of the baby being born prematurely in adolescent women was significantly higher than in high-risk group compared to reference group. Pregnancy related anxiety was measured in two groups [Table/Fig-4].

There was a statistically significant relationship between maternal age and perception of pregnancy risk (p<0.003). There was also a statistically significant relationship between pregnancy related anxiety score and perception of pregnancy risk (p<0.002).

In this study, we surveyed the maternal age related risk perception of pregnancy, because the main purpose of this study was to compare the differences of perception of pregnancy risk of the two age groups of healthy nulliparous women. According to our results, there were large individual variations in the perception of pregnancy risks, different age groups had different perceptions of pregnancy risk mean scores, the highest mean score of perception of pregnancy risk observed in both ends of the age spectrum (15 and 34 aged group women), it seems that the main concern related to the effect of maternal age on pregnancy begins around 35 years of age. Normal aged group of women had different perception of pregnancy risk, these findings confirm that risk perception in pregnancy is individualized [18].

Overall, women aged <18 years (high-risk group) perceived the risks of pregnancy higher than those aged 18 to 35 years (reference group). Women in high-risk group rated their risks for herself, having haemorrhaging, having a cesarean birth and dying during pregnancy to be significantly higher than those in reference group. Therefore, we recognized that risks in pregnancy were connected with age. This finding was confirmed with previous studies [9,19].

Results of previous qualitative studies showed that most high-risk women were concerned about risks associated with their pregnancies [9,20,21]. There is little quantitative and qualitative research on comparing differences in pregnancy risk perception of adolescent mothers and other pregnant women. However, findings of qualitative research showed that adolescents and pregnant: expressed negative perceptions of their bodies and self in pregnancy [22,23].

Our results showed that, high-risk group mothers perceived the pregnancy risk for herself more than their babies. The highest mean score of pregnancy risk perception of adolescent mother subscale was related to having a cesarean birth. Based on our results, the women aged <18 years perceived their risk of having a cesarean birth to be significantly higher than women aged 18 to 35 years. Due to the fact that the cesarean deliveries are not increased in adolescent pregnancies [24,25] may raise the question of whether fear of natural vaginal delivery, is a normal reaction to an unknown situation or other factors influences this perception [26-29]. The lowest mean score of perception of pregnancy risk subscale of women aged < 18 years was related to having the baby with birth defect, we thought, having prenatal screening for fetal health could be one possible explanation, because based on studies screening test reduces fetal health-related worries [30-32].

It has been shown that being labeled as high-risk and having risk information may increase anxiety [20]. In our study, all participants had relatively high mean level of anxiety, there was no statistically significant differences between them. Pregnancy related anxiety had statistically significant correlation with perception of pregnancy risk in all age groups, this is consistent with a similar research [33].

Perceptions of risk has a significant impact on the decision-making process, also for informing better decision-making, various risk communication methods are needed to accurately represent risk [34,35]. Knowledge of women about risk is important for professionals involved in the prenantal care. Health care providers need to develop effective counseling strategies for high risk pregnant women in this regard and more studies are required to ascertain the behavior of women, regarding the perceived risk of pregnancy for designing effective counselling strategies and developing more effective risk communication methods.

Firstly, the number of adolescent pregnant subjects was small, Secondly, this study can not be generalised to another population because risk perception is influenced by culture.

This study revealed that women’s perception of pregnancy risk is different in various maternal age groups. Maternal age can be considered as an important factor affecting perception of pregnancy risk. Perception of pregnancy risk of age related high-risk group was different from the reference group. Prenatal counselling, should include assessment of perception of pregnancy risk for health promotion and better pregnancy outcomes. Health care providers need to develop effective counseling strategies for high-risk pregnant women in this regard and more studies are required to ascertain the behavior of women, particularly those labelling as high-risk groups, regarding the perceived risk of pregnancy for developing more effective risk communication methods.