Introduction

Cervical ripening before the onset of labor is an important factor for the prediction of delivery mode, particularly in cases of labor induction. Increased cervical ripeness increases the likelihood of vaginal delivery and decreases the rate of cesarean section (1). For measuring cervical ripeness, Bishop scoring system can be used, which includes the rating of five components: cervical dilatation, effacement, position, and consistency, and fetal station in vaginal examination.

Higher Bishop score indicates higher cervical ripening and increased likelihood of vaginal delivery (1-3). Normally, Bishop score ≤ 5 indicates an unfavorable cervix, and Bishop score ≥ 8 indicates a high likelihood of spontaneous labor (3). According to the study of Williams et al. (1997), the ratio of cervical dilatation to total Bishop score and its components is a more reliable predictor of the success of labor induction and vaginal delivery (1, 2).

Changes related to cervical ripening usually occur during late pregnancy. In the last 6 to 8 weeks of pregnancy, through a process called “uterine awakening” or “activation”, the myometrium stillness is suspended and the number of myometrial oxytocin receptors is considerably increased. As a result, the number and surface area of GAP junction proteins such as connexin 43, also increase and uterine is prepared for labor contractions.

In addition, at about 34-36 weeks of gestation, the levels of estrogen and proges-terone hormones change within 5 weeks (2, 4). These changes together increase uterine irritability and its responsiveness to contraction-stimulating factors. Another impor-tant change in the myometrium is the formation of the lower uterine segment. At this stage, the cervix loses its integrated structure, and therefore, it becomes soft and dilated as soon as strong contractions begin (1, 4).

For a favorable cervical ripening, 1600 mmHg pressure is required, while if the cervix is not prepared, the pressure should increase to 10,000 mmHg (a 5-fold increase) (5). The exact mechanism of cervical preparation is unknown. However, several methods of cervical ripening have been introduced according to various theories including changes in estrogen and progesterone hormone levels, increased production of prostaglandins, increased sensitivity of the myometrium to oxytocin and prostaglandins, and interactions between these factors (1-4).

These methods include use of oxytocin and prostaglandins, mechanical surgery, and natural methods; oxytocin is the most common agent used worldwide (6, 7). Although the use of oxytocin is considered an effective method for cervical ripening, it is associated with multiple adverse side effects such as uterine hyperstimulation, intoxication with water, postpartum hemorrhage, embolism of amniotic fluid, and neonatal jaundice.

An ideal agent for cervical ripening should prepare the cervix for delivery with minimum complications for the mother and the fetus (8). Natural non-drug methods, including non-invasive techniques, are more effective, more economical, and safer than pharmacological methods. Current non-drug methods include castor oil, evening primrose oil, raspberry leaf, sisymbrium irio (London rocket), and date fruit (9).

Studies have shown that date fruit, a reinforcing fruit rich in carbohydrates, affects the progress and spontaneity of labor and reduces postpartum hemorrhage (10-12). Date is a reinforcing fruit rich in carbohydrates; these carbohydrates are simple sugars, absorbed and used by the cells shortly after consumption. Date fruit also contains vitamin B, iron minerals, calcium, magnesium, and potassium. Today, various studies have been conducted on different varieties of date fruit and many of its nutritional and health benefits have been determined (13-15).

In a study, the effect of date pollen on serum hormone levels was examined in female adult rats. The results showed that palm pollen extract can increase estrogen and progesterone levels in rat sera, but has no effect on Luteinizing hormone or follicle-stimulating hormone (16). It was also found that the consumption of date fruit increases the pain threshold and its intake in late pregnancy is recommended to accelerate labor (17).

Date fruit contains saturated and unsaturated fatty acids such as oleic, linoleic, and linolenic acids. Fatty acids in addition to providing and reserving energy, contribute to prostaglandin provision (15); therefore, date fruit can be helpful in saving energy and strengthening uterus muscles. It also contains hormones which help the uterus stretch and be prepared for child delivery (18).

According to the results of Alkoran and colleagues (2011), cervical dilatation on admission was higher in the group consuming date fruit during late pregnancy, compared to the non-consuming control group (P<0.0005). It seems that date fruit influences oxytocin receptors, stimulates the uterine muscles to respond more comfortably to oxytocins, and better prepares the uterus and cervix for delivery (10). Khadem et al. (2007) demons-trated that date fruit has oxytocin-like effects and its nutritional and therapeutic character-ristics reduce postpartum hemorrhage; it can also be a suitable alternative for oxytocin (12).

Given that the number of oxytocin receptors elevates in the last months of pregnancy, which itself leads to an increase of uterine sensitivity and contraction stimulation, date fruit can influence oxytocin receptors and accelerate the onset of uterine contractions more easily (10-12). Considering the limited research in this area and lack of such reports in Iran, we aimed to determine the effect of late-pregnancy consumption of date fruit on cervical ripening in nulliparous women.

Materials and Methods

This clinical trial was performed from 6th April to 2nd September 2013 on 210 primiparous women, referring to Mashhad Omolbanin Hospital, Iran. To calculate the sample size, a pilot study was performed on 20 patients. Then, considering α=0.01 and β=0.1, the sample size was calculated 96 cases in each group. Given a 10% loss of sample, 105 cases were included in each group (a total of 210 women).

First, the approval of the ethics committee of the university was obtained. After explaining the study objectives to the mothers and obtaining written consents (with regard to ethical principles for medical research), sampling was performed. The inclusion criteria were as follows: 1) primiparity, 2) 18 to 35 years of age, 3) 37-38 weeks of gestation, 4) singleton pregnancy with cephalic presentation, 5) lack of medical or gynecological problems, 6) no assisted reproductive technology (ART) pregnancy, and 7) non-elective cesarean section. Women in the intervention group, who used date fruit less than 2 weeks, were excluded from the study.

Considering the consumption of date fruit, the subjects were randomly divided into two groups: intervention and control groups (consuming and non-consuming groups, respectively). At the beginning of the sampling, week days from Saturday to Thursday were numbered 1 to 6. Then, using a table of random numbers, 3 days were randomly assigned to the intervention group and 3 days to the control group. Data collection tools included questionnaires, observation, physical examin-ation, form of fetal movement record, and the checklist related to daily consumption of date fruit.

Validity of data collection tool was determined by content validity. The tools were provided as preliminary questionnaires with regard to literature and the latest related research. They were given to 10 members of the School of Nursing and Midwifery, Mashhad University of Medical Sciences, and were finalized after review and modification. Reliability of the questionnaire was confirmed by the inter-rater reliability with a correlation coefficient of 0.94.

The used date fruits were the products of Mazafati Rotab Dates, purchased from major food distribution centers in Mashhad, Iran. The intervention group weekly received 7 packets of 70-75 gr date fruit since the 37th week of gestation, and the mothers were asked to continue the consumption up to the onset of labor (70-75 gr per day in three divided doses). On the other hand, the control group was asked not to eat date fruit during this period and recevied routine care.

Subjects in both groups, after entering the study, were evaluated in terms of the onset of labor. During the study period, they were trained to avoid using enema, nipple stimulation, use of laxatives, herbal or chemical drugs, or traditional methods of labor induction. Also, the mothers received the forms of fetal movement record, in which the researcher’s phone number (for emergency calls or asking questions) and the date and time of the subjects’ enrollment (in the study) were recorded.

Each week, participants in both groups were examined by the researcher in terms of vital signs, weight, fetal heart rate, fetal movements, uterine spotting, bleeding and discharge, probable outcomes of date fruit (in the intervention group), and use of date fruit (in the control group); the data were recorded in the follow-up form.

The mothers in each group were trained regarding the signs of labor onset. They were asked to inform the researcher and refer to Omolbanin Hospital if there were any signs of labor onset. If delivery was not starting until 40 weeks of gestation, both groups were asked to refer to the clinic for delivery checkups and tests of fetal health. If there were no problems in continuing the pregnancy in the control group, the mothers were trained about the signs of initiation of labor. In the intervention group, in addition to teaching these signs, they were advised to continue the consumption of date fruit.

If delivery was not starting until 41 weeks of gestation, the subjects were referred to the obstetrics ward for labor induction, where the researcher was present. After vaginal examination, the related details were recorded in the questionnaire and Bishop score was calculated for comparison between the groups. Data analysis was performed using SPSS version 14, and Chi-square and t-test. P value less than 0.05 was considered statistically significant.

Results

A total of 240 women were enrolled in the study. Five cases were excluded given their unwillingness to continue the study, 1 due to sensitivity to date fruit, 11 due to non-use of date fruit for at least two weeks, 9 due to labor induction before 41 weeks of gestation, and 5 due to gestational hypertension. Finally, 210 women remained in the trial.

The subjects were not statistically different in terms of mean age and body mass index (BMI). The mean age was 23.51 ± 3.67 years in the intervention group and 23.58 ± 3.73 years in the control groups (P = 0.89); also, the mean BMI was 22.88 ± 2.76 and 23.17 ± 2.67 kg/m2, respectively (P= 0.44).

Based on Chi-square test, the two groups were not statistically different in terms of education level, history of abortion, history of prolonged pregnancy in first-degree relatives, history of bleeding and spotting during the first trimester of pregnancy, use of non-steroidal anti-inflammatory drugs, or mother's education level (Table 1). Also, 84.8% (n=89) of subjects in the intervention group and 96.2% (n=101) in the control group were housewives; the two groups were matched in terms of occupation (P=0.42).

The results of Mann-Whitney test showed that the mean Bishop score at admission was higher in the intervention group, compared to the control group; the mean Bishop score was 7.67 ± 2.28 in the intervention group and 5.12 ± 2.77 in the control group (P <0.001). The Bishop score > 5 at admission was more frequent in the intervention group, compared to the control group at various weeks of gestation (P<0.001) (Table 2).

Values of each Bishop scoring component (cervical dilatation, effacement, position, and consistency, and fetal station ) were statistically significant in the two groups (Tables 3 & 4).

The rate of vaginal delivery was higher in the intervention group, but the groups were not statistically different in terms of delivery mode (P=0.09); the rates of cesarean section and vacuum/forceps were 8.6% and 1.9% in the intervention group and 15.2% and 3.8% in the control group, respectively. The use of oxytocin for labor induction in the intervention group (20%) (n=21) was significantly less than the control group (44.8%) (n=47) (P<0.001). Also, the success rate of labor induction (vaginal delivery after labor induction) in the intervention group (47%) was higher than the control group (28%) (P= 0.036).

Discussion

The results of the current study showed that the mean Bishop score was significantly higher in the group who used date fruit in the last month of pregnancy, compared to the nonconsuming group. The study of Alkoran et al. (2011), which evaluated the effects of date fruit on labor and delivery in nulliparous and multiparous women, showed that the mean of cervical dilatation at admission in the group, who used date fruit, was higher than the control group (P<0.005).

Also, in the study of Alkoran, occurrence of spontaneous labor was lower in the intervention group and these subjects required less labor induction. They noted that date fruit probably influenced oxytocin receptors, caused more effective contractions, and better prepared the cervix for delivery (10).

Iravani et al. (2006) performed a study with the aim to determine the efficacy and safety of castor oil in cervical ripening and labor induction. According to the results, spontaneous labor pain and mean Bishop score were significantly higher in the intervention group compared to the control group (P<0.001); in fact, castor oil, similar to date fruit, contains substances which can reinforce prostaglandin synthesis (19).

In addition, other substances such as evening primrose oil, raspberry leaf, and sisymbrium irio, given their prostaglandins and fatty acid precursors, have been assessed in several studies, and their effectiveness in cervical ripening has been shown. Based on the studies of Simpson et al. (2001), Mohammadinia et al. (2003), and Dow et al. (1999), use of raspberry leaf, sisymbrium irio, and evening primrose oil in late pregnancy positively affected cervical ripening, respectively (20, 21, 22).

Khadem et al. (2007), in a study by comparing the effects of date fruit and oxytocin in the prevention of postpartum hemorrhage, found that date fruit has an oxytocin-like effect, leads to the increased sensitivity of the uterus, stimulates uterine contractions, and reduces mean postpartum hemorrhage (12).

Date fruit contains saturated and unsaturated fatty acids such as oleic, linoleic, and linolenic acids, which are involved in saving and supplying energy and construction of prostaglandins. In addition, serotonin, tannin, and calcium in date fruit contribute to the contraction of smooth muscles of the uterus. Date fruit also has a laxative effect, which stimulates uterine contractions (12, 14).

In Qur'an, the holy book of Muslims, date fruit has been introduced as part of a healthy diet. As mentioned in Qur’an, God gave Mary fresh date fruit in the time of giving birth. According to Islamic Hadiths, if date fruit was not a rich food source, God would not have given it to Mary.

Date fruit contains 13 vital substances and 5 kinds of vitamins, fatty acids, and sugars. Thus, this fruit, which is rich in minerals, is recommended for pregnant women who need energizing and nutritious foods (18). Date fruit also influences estrogen and progesterone hormones, which are effective in preparing the uterus and cervical ripening (16).

The current research was not doubleblinded, which is a limitation of this study. Also, the amount and duration of date fruit consumption were not recorded, which highlights the importance of performing further studies. Finally, another limitation was lack of control over the mothers’ daily diet.

Conclusion

Cervical ripening was more favorable in women, who used date fruit, compared to the non-consuming group. Given that date fruit is an energizing and nourishing substance, its use is recommended for pregnant women during pregnancy, particularly during the final weeks of gestation.

Acknowledgment

This study was extracted from a research project, approved on 29/10/2012 by Mashhad University of Medical Sciences (code: 910732), and sponsored by the University Research Council. The authors appreciate the cooperation and assistance of the University Vice Chancellor for Research.

Conflict of Interest

The authors declare no conflicts of interest.