Final answer:
Pregnancy occurrence within 4 years of menarche puts a mother and fetus at risk due to factors such as the mother's physical and emotional immaturity, potential diversion of resources from the fetus, and social and economic challenges faced by teenage mothers.
Step-by-step explanation:
Pregnancy occurrence within 4 years of menarche places a mother and fetus at risk due to several factors. Firstly, younger mothers may not have the physical and emotional maturity to handle the demands of pregnancy and parenting, which can lead to inadequate prenatal care, unhealthy lifestyle choices, and higher risk of complications. Secondly, the mother's body may still be growing and developing, which can divert resources away from the fetus and increase the risk of birth defects and other complications. Finally, teenage mothers may face social and economic challenges that can negatively impact their health and the health of their fetus.