Final answer:
The statement that pregnancy is maintained by human chorionic gonadotropin (hCG), estrogens, and progesterone is true. These hormones are key in maintaining the pregnancy, protecting the fetus, and stimulating maternal and fetal development throughout the gestation period.
Step-by-step explanation:
The statement that pregnancy is maintained by human chorionic gonadotropin (hCG), estrogens, and progesterone is true. During pregnancy, several hormones play crucial roles in maintaining the pregnancy and supporting both maternal and fetal development. The outer layer of the blastocyst produces human chorionic gonadotropin (hCG), which is critical in preserving the corpus luteum. The corpus luteum, in turn, secretes progesterone to maintain the pregnancy. Progesterone prevents the development of new ovarian follicles and suppresses uterine contractility to protect the fetus. Additionally, estrogens are essential in maintaining the pregnancy, promoting fetal viability, and stimulating growth in the maternal tissues and the developing fetus.