Maternal nutritional status during pregnancy is the key to determining the health of newborns, especially the nutritional intervention in the third trimester of pregnancy. In this study, we observed the difference between 62 pregnant women who received nutritional management and care and 46 pregnant women who did not in the third trimester and found that the use of nutritional management and care could improve maternal nutritional status, reduce the risk of hyperglycemia, and increase pregnancy weight gain. Meanwhile, nutritional management and care helped to mitigate the negative psychology of pregnant women, increase the spontaneous labor rate, and reduce the risk of macrosomia and low-birth-weight infants. In terms of newborns, nutritional management and care improved their weight, height, head circumference, and so on, providing a more reliable guarantee for their physical health. According to the above results, we believe that nutritional management and care should be popularized in obstetrics and gynecology.