A client telephones the clinic to ask about a home pregnancy test she used this morning. The nurse understands that the presence of which hormone strongly suggest a woman is pregnant?
a. Estrogen
b. Progesterone
c. HCG
d. Alpha-fetoprotein Clear my choice
The correct answer and explanation is:
The correct answer is c. HCG (Human Chorionic Gonadotropin).
Human Chorionic Gonadotropin (HCG) is a hormone produced by the placenta shortly after the embryo attaches to the uterine lining. The presence of HCG in a woman’s urine or blood is the key indicator of pregnancy, and this is what home pregnancy tests are designed to detect.
During pregnancy, after fertilization and implantation, the developing placenta secretes HCG to support the pregnancy by stimulating the corpus luteum (a structure formed from the follicle after ovulation) to produce progesterone. Progesterone is critical for maintaining the uterine lining, preventing menstruation, and supporting early pregnancy.
HCG is detectable in urine as early as 10 days after conception, though levels increase rapidly and peak around 8 to 11 weeks of pregnancy. Home pregnancy tests generally detect a threshold concentration of HCG in urine, typically giving a positive result within minutes if the hormone is present at detectable levels.
Estrogen and progesterone levels also rise during pregnancy, but these hormones are not specific to pregnancy in the way HCG is. Estrogen and progesterone are important for supporting the pregnancy but are produced at high levels throughout the menstrual cycle, regardless of whether a woman is pregnant.
Alpha-fetoprotein is another important substance during pregnancy, but it is produced by the fetus and is used to assess the risk of certain birth defects or disorders, such as neural tube defects or Down syndrome. It is not a direct indicator of pregnancy in the early stages.
Thus, HCG remains the most reliable marker for confirming pregnancy.