The effect of short pregnancy interval on perinatal outcomes in Turkey: A retrospective study

Objective: The aim of the study was to determine the effect of short pregnancy interval on perinatal outcomes. Methods: The research was a retrospective study. The material consisted of birth records of a state hospital for the last three years in Manisa in the western region of Turkey (2015-2017) (n:8961). The research population included women whose gestational interval was ≤two years and the gestational week was over 22 weeks (n:2089). Perinatal outcomes were assessed through preterm birth, stillbirth, and low birth weight. Results: The mean age of women who are in the research group is 26.7 ± 5.32. According to the perinatal results of women with a pregnancy interval of two years and shorter; 8.2% of women had birth before 37 weeks and 0.3% resulted in stillbirth. It was determined that 4.8% of infants were born with low birth weight. There was no difference between the short pregnancy interval and stillbirth or preterm birth. However, a significant difference was found between the low birth weight and short pregnancy interval. (p>0.05). Conclusions: Pregnancy interval does not affect preterm birth and stillbirth from perinatal outcomes, but has a significant effect on the birth weight of the newborn.


INTRODUCTION
The World Health Organization states that the pregnancy interval is time between the delivery date of the preceding live birth and conception date of the index pregnancy in women who have had more than one birth. 1 The risk of complications increases in pregnancies that occur less than two years and they are considered to be highrisk pregnancies. High-risk pregnancies are of particular importance because of increased risk of illness or death before, during, and after birth. 2 Nonoptimal pregnancy interval that is either too short or too long contributes to adverse maternal and perinatal outcomes in both low and high income countries. 3 The other studies conducted on this issue support the results of this research. [4][5][6] Especially short pregnancy interval of less than 18 months have been associated with several bad fetal and neonatal outcomes such as pre-term birth, low birth weight (LBW), stillbirth, and newborn/infant mortality. 5 Regardless of the gestational age, babies under 2500 grams of birth weight are considered "low birth weight". 7 The short period of time between the two pregnancies is reported to cause inadequacy of the renovation of the mother nutrient depot and consequently cause the baby to born with low birth weight. 8 There is 22.8% chance of low birth weight in short pregnancy interval as compared normal pregnancy interval (12.1%). 9 Short pregnancy interval is also a risk factor for preterm birth. 10 Short pregnancy interval can cause preterm birth by increasing the risk of cervical insufficiency and infection. 11 Preterm birth is prevalent up to 5% to 7% of among live birth in urbanized countries. 12 It has been reported that the rate of preterm birth <37 weeks was higher in women with short pregnancy interval <12 (20.1%) compared with normal pregnancy interval (7.7%). 13 The risk of neonatal death due to short pregnancy interval is high. The perinatal mortality was increased by 3-4 times in patients with an interval of fewer than 12 months between pregnancies, while infant mortality was increased by 2 times. 11 Different cut-off points have been considered for nonoptimal pregnancy interval in the literature.
The optimal pregnancy interval (24 months) was considered as the cut-off point in this study. The aim of this study was to determine the effect of short pregnancy intervals on perinatal outcomes.

METHODS
The research is a retrospective study. The research used the birth records of a state hospital in Manisa in the western region of Turkey for the last three years The data of the study were collected using a data collection form consisting of 21 questions. The data collection form was created by evaluating the data where the records that can be obtained through the system are complete. We evaluated three adverse perinatal outcomes: low birth weight (less than 2500 g), preterm birth (birth at less than 37 weeks' gestation), and stillbirth. Number, percentage distribution and Chi-square test were used for the evaluation of research data. The study received approval from Medicine Health Sciences Ethics Committee of Manisa Celal Bayar University Faculty and state hospital.

RESULTS
The time between two pregnancies in 55.0% of women in the research is shorter than 2 years. The mean age of women is 26.7 ± 5.32. The number of pregnancies for 44.4% of women was 2, and 52.9% had 2 live births. It was determined that 3.7% of the women in the research group had a chronic disease, and 9.8% were smoking (Table-I The previous pregnancy of approximately 84.0% of women has resulted in a birth. The gestational age of birth for 0.8% of women (according to the ultrasound) is 33 weeks and below. It was determined that 1.1% of women had a pregnancyinduced disease and 36.7% had anemia (hemoglobin value was under 11.0 g/dl) ( Table-II).
Looking at the characteristics of infants in the research; 99.7% were born alive, 99.5% of newborns were singular, 48.6% were female. The weight of 0.7% of infants are 2000g and below; 23.8% shorter than normal. The first minute of the APGAR score of 0.9% of the infant was between 0-6, and the fifth minute APGAR score of 0.4% of the infant was determined to be between 0-6. In addition, 8.7% of infants were determined to need intensive care (Table-III). The short gestational interval had no significant effect on preterm birth and stillbirth but it was determined to create a significant difference in terms of birth weight (Table-IV, p<0.05).

DISCUSSION
The study showed that 55% of women become pregnant in less than two years. In a study of pregnancy interval results in Israel, it was reported that the pregnancy interval short than 24 months was 54.1%. 14 In a prospective cohort study, 26.5% of the women included in the study had a pregnancy repeat within 18 months. 15 It was found that this rate was 18.8% when the research data were reevaluated according to gestation intervals of 18 months. The research findings are consistent with the relevant literature. 84.0% of women's previous pregnancy resulted in birth. In a study where the effects of pregnancy interval were investigated, 89.5% of pregnancies resulted in birth. 16 In the study, 8.2% of the births occurred before 37 weeks. It was found that the short pregnancy interval did not have a significant effect on preterm birth. The short pregnancy interval has been recognized as a risk factor for preterm birth. 17 It was found that the short pregnancy interval is related with preterm birth rates according to the studies which were conducted in different countries as Tanzania and Canada. 18,19 Contrary to this it was determined that short pregnancy intervals were not related with preterm birth rates in a study conducted in Pakistan which is similar to the findings of this study. 20 The study also found that 0.3% of women had given stillbirth and the pregnancy interval did not have a significant effect on stillbirth. There are almost 3.2 stillbirths per 1000 births all over the world each year. The highest absolute numbers (approximately stillbirth rates are 32 per 1000) of stillbirths occur in Sub-Saharan Africa and South Asia. 21 However ın many high-income countries (Europe, North America and Australia vb.), for every neona- tal death there are now approximately 1.7 stillbirth (stillbirth rates are below 5 per 1000 births). 22 The stillbirth rate in Turkey is 1 per 1000 births. 23 The stillbirth rate of Turkey is on the level of developed countries. The stillbirth rate which was found in this study is lower than the rate for stillbirths of Turkey. The data for the research were acquired from the last three years' data of a single hospital, therefore it supposed that there is not a significant relationship between stillbirth and short pregnancy interval. It was determined that 4.8% of infants were born with low birth weight and that the short gestational interval created a significant difference in terms of baby's birth weight. According to the data of the Turkish Population Health Survey (2013); 10% of the children whose birth weight are known are at a low birth rate. 23 Zhu et al determined that women with short pregnancy intervals had an increased risk of low birth weight in their babies. 24 The findings of the researchs which were conducted in Egypt, 25 Iran 26 and Turkey 27 have shown similar results. The present research findings are consistent with the literature.

CONCLUSION
In this study, where the effect of short gestational intervals on perinatal outcomes is investigated, perinatal results were evaluated in three Nevsen Saral et al.  subheadings. Pregnancy interval does not affect preterm birth and stillbirth from perinatal outcomes but has a significant effect on the birth weight of the newborn. Furthermore, more than half of the women who were included to this study conceived before the optimal pregnancy interval in this study. It supposed that increasing to take proper contraceptive medicines and raising awareness of women for perinatal outcomes are important for both women and children health aspects.

Limitations of the study:
The data of the research is from a single hospital for a period of three years.
Financial support: No financial support was received for the research.