In the present study, we found that the percentage of women who reported increased/excessive fetal movements was relatively higher in those who had the first-time pregnancy compared the control group. This incidence rates dropped in those who had a history of pregnancy. This phenomenon may be due to the first pregnancy, during which pregnant women are not experienced in the method of counting fetal movement and appear more sensitive and cautious during counting. Hence, these first-time pregnant women may report increased fetal movements more frequently, which might compromise the objectivity of data in the current study. In fact, increased/excessive fetal movement is quite a common experience after 37 weeks of gestation. Therefore future investigations should include more objective measurements to address this limitation.
One important finding in our study is that, most of the neonates with increased fetal movement did not show poor prognosis. Instead, we observed better prognosis, which was reflected in the lower percentage of pre-term infants in women who had increased fetal movement. The neonatal weight of the newborns was significantly higher in women who had increased fetal movement than those of the control group. However, this may be also due to a higher percentage of pre-term infants in the control group, resulting in a decrease in the weight of newborns in the control group. Furthermore, in women who had increased fetal movements, we observed that increased fetal movements appeared mainly between 31 and 39 weeks of gestation. This increased fetal movement at 31 weeks of gestation is likely because that fetal weight gain is in an accelerated period, when the fetal movement may be frequent and obvious. At the 39th week of pregnancy, the frequency of false contractions increased, coupled with the proximity of childbirth. These factors may also contribute to the enhanced consciousness of fetal movement in women. Furthermore, our findings that about 9.6% pregnant women reported experience of increased/excessive fetal movements were similar with previous reports. In the situation, task, actions, and results (STARS) cohort study, 1714 women were recruited from more than seven countries, and 8.5% of respondents reported excessive fetal movements [11]. Among the respondents, the symptom frequency from the four major countries who participated in the survey remained consistent. Similarly, the frequency of perceived excessive fetal movements was close to that of the 10% of women who was analyzed in a stillbirth study in Sweden [12]. Interestingly, similar to our report, the perception of excessive fetal movements was reported more frequently (12% of respondents) when gestation was beyond 37 weeks [12]. Together with our reports, these results suggested that women in the third trimester of pregnancy may encounter more frequent excessive fetal movements.
Another important finding in our study is that, our regression analysis found that higher odds of LGA were associated with women who had increased/excessive fetal movements and gestational age over 37 weeks. One of the primary risk factors of LGA is poorly-controlled diabetes, particularly gestational diabetes, as well as pre-existing diabetes mellitus [13,14,15,16], which increase maternal plasma glucose and insulin levels, as well as stimulates fetal growth. In addition, studies have shown that gestational age more than 40 weeks and excessive maternal weight gain can increase incidence of LGA [15]. Consistent to this literature, our study confirmed that gestational age over 37 weeks was associated with increased incidence of LGA. Furthermore, women with increased/excessive fetal movements also had higher incidence of LGA, particularly when the gestational age was more than 37 weeks.
Changes in amniotic fluid may indicate fetal intrauterine hypoxia, fetal acidosis in the fetus, and the abnormal fetal growth [17, 18]. Surprisingly, we did not observe any difference in amniotic fluid volume or degrees of stained amniotic fluid in women who had increased fetal movement when compared to those of the control group. In addition, there was no correlation between increased fetal activity and the incidence of umbilical cord around the neck. These results suggested that amniotic fluid volume and contamination and the incidence of umbilical cord around the neck may not be the contributing factors in increased fetal movements.
While our study did not report increased cases of stillbirth in women who experienced increased/excessive fetal movements. Case-control studies have been performed in order to examine if there is any difference in the frequency of increased/excessive fetal movements between pregnancies with live births and those with stillbirth. In the Auckland Stillbirth Study, women who had stillbirth experienced more single episodes of excessive fetal activity [19]. However, more than one episode of vigorous fetal activity was less likely perceived by those who had stillbirth. In addition, women who had stillbirth were less likely to report the perception of increased fetal movements compared to controls [19]. Furthermore, one episode of vigorous activity was more likely perceived by women who had stillbirth in the STARS study [20]. Hence, these results suggest that a sudden episode of excessive fetal activity may indicate the compromise of fetus that is related to the disturbance of environment in uterus. Future studies with a larger cohort will be necessary to examine this hypothesis.
