hCG (Human Chorionic Gonadotropin)

The 'pregnancy hormone' detected by tests, responsible for sustaining early pregnancy.

What is hCG (Human Chorionic Gonadotropin)?

Human Chorionic Gonadotropin, commonly known as hCG, is a hormone produced primarily by the cells in the placenta during pregnancy. It is often referred to as the 'pregnancy hormone' because it is the specific chemical detected by both home urine tests and clinical blood tests to confirm conception.

The primary role of hCG is to maintain the corpus luteum—a temporary gland in the ovary that produces progesterone. This progesterone is vital for keeping the uterine lining thick and supportive, preventing the body from shedding it (which would result in a period) and allowing the pregnancy to progress.

When Does hCG Appear?

hCG production begins almost immediately after a fertilized egg implants into the uterine wall, which typically occurs about 6 to 12 days after ovulation.

• Blood Tests: Can detect hCG as early as 8–11 days after conception.
• Urine Tests: Most 'early detection' home tests can detect hCG about 12–14 days after conception (around the time of your missed period).

hCG Levels and Trimester Progression

In a healthy pregnancy, hCG levels rise rapidly, typically doubling every 48 to 72 hours during the first several weeks. They reach their absolute peak around the end of the first trimester (weeks 10–12) and then gradually decline and level off for the remainder of the pregnancy.

What High or Low Levels Mean:

• Rapidly Rising/Very High Levels: Can indicate a multiple pregnancy (twins or triplets) or, in some cases, a molar pregnancy.
• Slowly Rising/Low Levels: May unfortunately be a sign of a potential miscarriage or an ectopic pregnancy (where the embryo implants outside the uterus).

Note: There is a massive range of 'normal' hCG values. A single number is less important than the trend of how the levels are increasing over time.

The Side Effects of hCG: Morning Sickness

While hCG is essential for baby, it's often the culprit behind one of the most famous pregnancy symptoms: nausea and vomiting, or 'morning sickness.' The peak of morning sickness usually aligns perfectly with the peak of hCG levels at the end of the 12th week.

The Bottom Line

hCG is the first chemical signal that a new life has begun. By tracking your ovulation precisely with the Bloom App, you can know exactly when to take an hCG test and avoid the 'two-week wait' anxiety.