The pregnancy stage has a profound effect on the life of every woman and is associated with physical and psychological changes. During this period, attention to the health of the fetus is of particular importance [1, 2]. The maternal mortality rate due to elective Cesarean Section (CS) is 2 to 3 times higher than that of natural delivery . The high rates of CS increase maternal (such as uterine infections, postpartum hemorrhage, and anesthesia) and neonatal (such as increased length of hospital stay in the neonatal intensive care unit, respiratory diseases, jaundice, neonatal infection, low Apgar score, low birth weight, and neonatal mortality) complications [3, 4].
Prenatal care and type of delivery for nulliparous pregnant women have a great impact on their experience of pregnancy and delivery and can also determine the type of their next delivery . In the health system transformation plan, the promotion of natural childbirth is pursued with the general goal of improving the health indicators of mothers and infants by reducing the CS rate . However, one of the complications of natural childbirth is episiotomy which is much more common in Iran than in other countries . Episiotomy has such side effects as delayed wound healing, increased risk of infection, fatigue, insomnia, difficulty in sitting and holding the infant, decreased sexual function, and impaired emotional relationships between the mother and infant . In their study, Firuzbakht et al. reported the effect of childbirth preparation classes and exercises on reducing the rates of episiotomy and emergency CS .
There is a problem of reduced physical activity during pregnancy so that 60% of women become sedentary during this period . On the other hand, due to their lack of awareness about the benefits of exercise during pregnancy, women are reluctant to exercise . Exercise during pregnancy has a high priority in terms of health and care due to its benefits for the mother and fetus .
Exercise during pregnancy is one of the best ways to reduce pregnancy complications such as insomnia, feeling tired, excessive weight gain of mother, back and low back pain, pelvic pain, constipation, urinary incontinence, hypertension, gestational diabetes, depression, and anxiety. In addition, exercise increases individuals’ ability to adapt to activities related to infant care .
There are different types of physical activities during pregnancy, such as yoga, pregnancy gymnastics, Pilates, and Kegel exercises. One of the physical activities that pregnant women tend to do is pregnancy yoga . Numerous studies have shown that yoga improves the outcomes of low-risk and high-risk pregnancies . Yoga interventions contribute to both physical and psychological health. They improve muscle strength, memory, and sleep quality and reduce pain and depression . In ancient Indian science, yoga has been described as a lifestyle including changes in mental attitude and diet besides the practice of certain techniques . Yoga is an ideal way to spend the pregnancy period .
Yoga during pregnancy allows pregnant women to make connections with their mind, body, soul, and fetus [1, 15]. Field et al. concluded that yoga exercises during pregnancy reduced anxiety, depression, and the back and pelvic pains and led to delivery at an appropriate gestational age and the normal birth weight of infants . In their study, Jahdi et al. examined the effect of yoga on the severity of labor pain and the outcomes of labor and reported the significant effect of yoga on reducing CS and induction of labor . Furthermore, Ostrovesky stated that yoga during pregnancy can reduce the rate of CS and labor pain .
Yoga is usually a combination of mental exercises, meditation, various types of deep breathing, stretching, and relaxation [1, 18]. Meditation is a specialized exercise which provides deep relaxation to calm the body and focus the mind . The benefits of yoga include a better physical growth, stronger and more flexible muscles and joints, and the reduced risks of preterm delivery, hypertension due to pregnancy, and intrauterine growth restriction . Yoga techniques are non-invasive and have fewer side effects  and so far no study has reported the side effects or negative effects of yoga exercises on the physiological or psychological outcomes of pregnant mothers [1, 14].
Yoga exercises during pregnancy can reduce the risks of preterm delivery, intrauterine growth restriction, preeclampsia (high blood pressure during pregnancy), emergency CS, and fetal death [21, 22]. In their study, entitled “the effectiveness of yoga on pregnancy outcomes (pregnancy age and infant weight)”, Narendran et al. reported that the abnormal birth weight, preterm delivery, intrauterine growth restriction, and gestational hypertension were significantly lower in the yoga group than in the control group . In their study, Rakhshani et al. examined the effect of yoga on the pregnancy outcomes of 68 women with high-risk pregnancy and showed that pregnancy yoga reduced the outcomes of gestational diabetes, hypertension, preeclampsia, and intrauterine growth restriction, and preterm delivery, low birth weight of the infant, and low Apgar score .
Given that pregnancy yoga is a non-invasive technique with few side effects, that no study has been found on the side effects or negative effects of yoga exercises on pregnant women, and that yoga can be performed by most pregnant women, also due to the contradictory results in some studies and few studies regarding the effectiveness of this type of yoga in nulliparous women the authors decided to conduct a study to investigate the effects of yoga on pregnancy, delivery, and neonatal outcomes in Qazvin, Iran.