In the study we found low parity was not associated with macrosomia in Western China. With the improvement of the living standards of Chinese people, the incidence of fetal macrosomia has increased [11,12,13,14,15]. It has been shown that multiple parities can lead to the relaxation of the peritoneum and uterine wall, an increase in uterine volume, and an extension of the duration of pregnancy preservation after multiple pregnancies, which leads to an increased risk of macrosomia [1,16,19,20,21,22]. We hypothesized that macrosomia incidence in second children will increase. However, the findings refuted our hypothesis. Furthermore, the birth of a second child with macrosomia was not significantly related to the occurrence of macrosomia in the first child. However, this finding is not without practical significance. Some studies have shown that increased parity is associated with a high risk of fetal macrosomia[21,22]. In a study from Sack, mothers with multiple pregnancies had a higher risk of having fetal macrosomia than those in the control group did . Dor et al. reported that the multiparity rate was approximately 70% in the case group. Similarly, the study of Akin Usta et al. showed a multiparity rate of 64% among mothers with fetal macrosomia and a significantly higher parity in the macrosomia group than in the control group . Results from the aforementioned studies are based on mothers with more than two pregnancies. By contrast, the current study focused on only the first and second pregnancies. Therefore, potentially removing the effects of peritoneal and uterine walls and the uterine cavity volume of pregnant women on giving birth to a second child is possible. In the context of China’s “two-child policy,” we have strong evidence that suggests that Chinese mothers may not have to be concerned with the possibility of having a second child with macrosomia. In the Chinese context, the increase in the incidence of macrosomia may be mainly due to the increase of obesity and other chronic diseases. The prevention of fetal macrosomia should give priority to lifestyle intervention and prevention of obesity.
We found that among the second pregnancy, there was no association between the history of first child macrosomia and the second child macrosomia, history of first child macrosomia was not a predictor of second child macrosomia. This finding may indicate that for two pregnancies of the same woman, the birth of a second child with macrosomia is not related to whether the first child had macrosomia.
This study found that mothers older than 30 years are less likely to give birth to babies with macrosomia. The finding is inconsistent with studies in other countries. For example, it has been shown that mothers aged 30 years may be at risk for macrosomia in Tanzania . A study conducted in the United Kingdom showed that the incidence of macrosomia in women between 35 and 39 years increased by 40% as compared to women under 35 years old. Our research also showed that the compared with those in the second pregnancy group, the mothers in the first pregnancy group were older and received higher education. We speculate that this result may be due to the fact that relative to pregnant women under the age of 30, pregnant women over the age of 30 in China are more educated and have better cognition of maternal and child health care. Studies also showed that mothers with higher education have a lower risk of macrosomia than mothers without higher education have. However, mothers in their second pregnancy may possibly have extensive knowledge or education about pregnancy-related health. Education has been recognized as the most important social factor affecting the health of mothers and children . Health and perinatal-educated mothers can maintain a healthy lifestyle, which is important for avoiding poor perinatal outcomes . Previous studies showed that the risk factors for perinatal outcomes such as macrosomia are clearly related to perinatal education [28,29]. Although the first pregnancy group reported higher education levels, the second pregnancy group had more perinatal experience, which may be the reason why no significant difference was found in the macrosomia incidence between the first and second pregnancy groups. In the context of China’s universal two-child policy, we believe that community and health departments should strengthen perinatal health education, which potentially plays an important role in preventing macrosomia and other adverse pregnancy outcomes.
An inverse association between physical activity and macrosomia was consistent with current knowledge. The American College of Obstetricians and Gynecologists, the Royal College of Obstetricians and Gynaecologists, and the Royal College of Midwives collectively recommend 30 minutes of daily moderate-intensity physical activity for low-risk pregnant women regardless of the stage of pregnancy[30,31,32]. Regular physical activity can lower the risk of gestational diabetes and thus reduce the macrosomia incidence [31,33,34]. However, among many Caucasian women with high education and income, there was a misperception that physical activities may be unsafe, exhausting, and uncomfortable, hence their inactivity[35,36]. It is unknown whether the same misperception exists among Chinese women as the prevalence of adequate physical activity.