Folic acid antagonists, which include such common drugs as trimethoprim, triamterene, carbamazepine, phenytoin, phenobarbital and primidone, may increase the risk not only of neural-tube defects but also of cardiovascular defect, oral clefts, and urinary tract defects. Folate supplementation before conception and during the first trimester reduces the risk of having infants with neural-tube defects and has the potential to reduce the risk of having infants with other congenital malformations and Down’s syndrome. Long-term use of multivitamins containing folic acid may reduce risks for hypertension, colon cancer, and breast cancer. The fortification of enriched grain products with folic acid also reduces the number of middle-aged and older adults with hyperhomocyteinemia, which is known to be a risk factor for deep-vein thrombosis, myocardial infarction, dementia and Alzheimer’s disease, congestive heart failure, and osteoporotic fracture. Therefore, folate supplementation has the potential to reduce the risk of a wide variety of conditions and diseases. For example, treatment with folate and mecobalamin (B12) reduced risk of hip fracture successfully in elderly patients with hemiplegia following stroke in a Japanese population. However, compared with specifically supplemented/fortified foods, consumption of naturally-occurring levels of folate in non-supplemented/fortified foods has been shown to be relatively ineffective at increasing folate status. Therefore, advice to consume folate-rich foods as a means of optimizing folate status may be misleading. Rather, increased folate intake with supplements is highly recommended.

Objective (1)To study the change of fetal middle cerebral artery pulsatility index (PI_MCA) in twin pregnancy; (2)To compare the singleton and twin pregnancies with regard of changes in PI_MCA over the course of the pregnancy. Methods Fetal middle cerebral artery flow velocity waveforms were measured in 34 cases of normal twin pregnancies and 176 cases of normal singleton pregnancies from 23～35 gestational weeks. Results PI_MCA in twin pregnancies exhibited a decrease trend toward the gestation. Before 29 weeks' gestation the PI_MCA in twin pregnancies was lower than that of the singleton pregnancies,and it was rather higher than that of the singleton pregnances after 29 weeks'gestation. Conclusions The vascular resistance in middle cerebral artery after 29 weeks of gestation was higher in twin pregnancies than that of the singleton pregnancies.