法苑珠林 69.44

69.44

又處胎經云。人受胎時。初七日有四大。二七日展轉風吹向脇。乃至三十八七日風名華。令向產門。

Furthermore, the Sūtra on Dwelling in the Womb says: When a human takes conception in the womb, during the first seven days the four great elements are present. In the second seven days, a shifting wind blows [it] toward the flank. Up to the thirty-eighth period of seven days, a wind named 'Flower' turns it toward the birth canal.