Nutritional management and suitable weight control during pregnancy are very important. However, in clinical practice, it is difficult to determine in detail precisely what pregnant women are eating. We investigated nutritional balance and nutritional requirements in pregnant women and their relationship to the course of pregnancy. A Food Frequency Questionnaire Based on Food Groups (FFQg) was distributed to 223 women at 12 weeks gestation attending one obstetrics clinic. We observed the women’s statuses until delivery and obtained information on pregnancy, delivery, and newborn from their medical records. One hundred and forty-seven (65.9%) of the subjects had problem-free pregnancies. Only 2 (0.9%) subjects developed pregnancy-induced hypertension syndrome. Participants were classified by pre-pregnancy BMI (body mass index; kg/m²) as follows: 44 (19.7%) were underweight (BMI < 18.5); 164 (73.6%) were of normal weight (BMI 18.5-24.9) and 15 (6.7%) were overweight (BMI < 25.0). Average infant birth weight was significantly lower in the underweight group than in the normal group (P < 0.05). There was no relationship between outcome of pregnancy and pre-pregnancy BMI. There were no marked differences in daily nutrients consumed among the three groups. However, the underweight group consumed significantly more fat than the normal group and gained significantly more weight before delivery than the others. Blood pressure was significantly higher in the overweight group than in the other groups at some points of gestation, although it remained within the normal range. Fat intake overall was more than the recommended value, especially in the underweight group. The relationship between course of pregnancy and nutritional intake was unclear. However, pre-pregnancy BMI may influence the course of pregnancy in terms of infant weight, gestational weight gain, and blood pressure.