Q: I am 5 weeks and 4 days pregnant. I just had a sonogram done and the doctor told me she could not see the corpus luteum. I know the corpus luteum is necessary to produce enough of progesterone to support the pregnancy. Is it a problem? Is my pregnancy progressing well or in danger?
A. There is no scientific evidence that the size or shape of the corpus luteum in early pregnancy is associated with any pregnancy complications such as an early miscarriage.
After ovulation, the corpus luteum, the area inside the ovary from which the egg was ejected, produces a hormone called progesterone. Progesterone prepares the lining of the uterus for implantation. After implantation, the corpus luteum will continue to produce progesterone to support the developing pregnancy until the placenta takes over around week 10-12 weeks.
Sometimes, the corpus luteum appears to not produce enough progesterone to support the pregnancy, possibly resulting in an early pregnancy loss. This is called 'corpus luteum insufficiency' or 'luteal phase defect (LPD). There are many reports contradicting this assertion, so there is no convincing evidence that luteal phase defect (LPD) is associated with an increase in infertility or miscarriage (HERE).
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