The meaning is that if the birth goes smoothly, the mother will smell the aroma of her family stewing chicken soup with sesame oil, the traditional tonic for new mothers. If there are problems during birth, they must prepare a casket.
意思就是：生產順利就可聞到家人為產婦燉麻油雞酒進補的香味，若碰上難產，就得準備棺材板了。