The pregnancy hormone: A complete guide to hCG levels, testing & imbalance

Once Pregnancy occurs, it is important to understand the hormones responsible for this process. These include hormones like progesterone, estrogen and prolactin. However, there’s one specifically called “the pregnancy hormone.” And that’s what we’re going to be looking into in this article. What is it, and when should you be concerned about abnormal levels?

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What is the Pregnancy Hormone?

The Human Chorionic Gonadotropin (hCG) hormone is largely produced in the placenta (the organ that connects the developing baby to the mother's uterine wall). hCG production begins shortly after a fertilized egg implants in the woman's uterus, around 6-12 days after conception.

This hormone signals the body to maintain the pregnancy by preventing menstrual period and supporting progesterone production. As hCG levels rise, it triggers the classic early pregnancy symptoms women experience: nausea, fatigue, breast tenderness, and frequent urination.

hCG also prepares the uterus for gestation, indicates multiple pregnancies as twins or triplets show higher levels, and supports fetal development by helping to produce other pregnancy hormones.

Note: In non-pregnant women, hCG exists in small, undetectable amounts but rises quickly in pregnancy. It’s also responsible for a lot of the changes many women experience.

Normal hCG Levels During Pregnancy

Once the body starts producing the hCG hormone, it increases throughout the first trimester before stabilizing and then declining after birth. According to the American Pregnancy Association, here is what to expect at each stage:

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This chart is not an absolute guide as some women's hCG levels could be on the higher or lower end of the range. However, this is normal for healthy pregnancies and can be caused by factors including: 

• Multiple pregnancies
• Miscalculated due dates
• Individual variation
• Certain medical conditions like ectopic or molar pregnancy

The most important thing is monitoring the levels regularly, and how they change over time. This can be done by a healthcare provider through tests that observe the range over a few days.

Testing for hCG Levels During Pregnancy

Since the HCG hormone is only detectable in pregnant women, it is the single factor used for qualitative pregnancy testing. This can be done in two ways:

1. Urine tests:

This involves using a sample of pee to confirm the presence of hCG, and it can detect this hormone once the levels reach 20-25 mIU/mL (usually 12-14 days after conception). However, it doesn't show how high or low the level is. This test can be done at home.

2. Blood tests:

Here, a blood sample is taken to check for the level of hCG in the blood. These tests are more sensitive, and can detect hCG at lower levels of 5 mIU/mL. Using this method shows the exact timeframe of the pregnancy.

Despite all these, it is still possible to see a lower level of hCG due to factors like:

• Testing too early: Even after conception, hCG levels might not be high enough to detect yet. This is why most healthcare providers recommend waiting until the first day of a missed period to test.
• Diluted urine: Doing a test after drinking large amounts of water may dilute the hCG in your urine, so it is advised to use first-morning urine since it typically has the highest hCG concentration.
• Expired or faulty tests: These can give inaccurate results so always check the expiration date and follow instructions carefully.

How Long Does the Pregnancy Hormone Stay in The Body?

After a woman stops being pregnant, the hCG hormone doesn't disappear immediately. Instead, it gradually decreases for about 4-6 weeks before returning to non-pregnant levels (less than 5 mIU/mL).

• After delivery: The hCG levels return to normal within 4-6 weeks, but this could be longer for women with multiple pregnancies.

• After a miscarriage: The timeframe depends on how far along the pregnancy was. With early pregnancy losses, hCG levels return to normal within 2-3 weeks, while more developed pregnancies can take 4-6 weeks or longer.

• After an ectopic pregnancy: hCG levels can take up to 8 weeks to normalize.

If the hCG levels don't drop after 6-8 weeks, you have to see a doctor especially if you’re experiencing other symptoms like heavy bleeding, severe pain, fever, or hormonal imbalance complications.

Signs of Hormone Imbalance After Pregnancy

After pregnancy, it is normal to experience mild hormonal fluctuations but they should not be ignored especially in cases of:

1. Continuous Positive Pregnancy Tests

If a woman still gets positive tests 6-8 weeks after delivery or pregnancy loss, her hCG levels may not be dropping normally. This could indicate retained placental tissue or, rarely, gestational trophoblastic disease.

2. Irregular or Absent Periods

Normally, periods can take a while to regulate after pregnancy, but very irregular cycles or absent periods beyond 3 months may indicate hormonal issues.

3. Unusual Bleeding

Heavy bleeding that happens weeks after pregnancy could indicate retained placental tissue or other complications.

4. Physical Symptoms

Constant nausea or vomiting, breast tenderness, unexplained weight changes, severe fatigue, and heart palpitations or dizziness.

Most often, these hormonal imbalances are caused by:

• Retained Placental Tissue: This can continue producing hCG and cause bleeding, infection, plus a delayed return to normal hormone levels.
• Gestational Trophoblastic Disease: A rare condition where abnormal cells grow in the uterus after pregnancy.
• Thyroid Dysfunction: Pregnancy and postpartum periods can trigger thyroid problems, affecting metabolism, mood, and energy levels.
• Breastfeeding-Related Hormones: Sometimes, the hormones involved in milk production can affect menstrual cycles and mood.

Pregnancy hormone imbalance can be dangerous, if not detected on time. So, it is important to visit the hospital and get checked if any of these symptoms persist over a few weeks.

Conclusion

The pregnancy hormone (hCG) plays a crucial role in maintaining pregnancy, preparing the mother's body for changes, and supports the baby's development. Understanding normal hCG levels, how tests work, and what happens after delivery can help recognize when something's wrong.

While hormonal changes are normal during pregnancy and postpartum, certain symptoms need immediate attention. Whether you're currently pregnant, recovering from pregnancy, or know any woman who is, tracking symptoms with healthcare professionals ensures the best outcomes for both mother and child.

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