OVERVIEW

How is biochemical pregnancy determined through biochemical testing?

The outer trophoblast cells of a fertilized egg can secrete human chorionic gonadotropin (hCG).

After the fertilized egg implants (occurring 6–12 days after ovulation), hCG is secreted and enters the bloodstream. Blood tests can measure hCG levels to determine whether pregnancy has occurred.

What is biochemical pregnancy?

For women who have not used contraception, experienced delayed menstruation, and have elevated hCG levels, continuous blood hCG monitoring reveals that pregnancy failure (miscarriage) is highly likely within the first 6 weeks of pregnancy, with a probability of about 30%.

After pregnancy failure, vaginal bleeding occurs, which closely resembles a normal menstrual period. As a result, many women mistake it for simply a delayed period.

Since the confirmation of pregnancy relies on blood hCG testing—a form of biochemical testing—this early pregnancy failure within 6 weeks is referred to as "biochemical pregnancy," also known as subclinical pregnancy.

In simpler terms, biochemical pregnancy refers to a situation where blood hCG is positive, but miscarriage occurs within 6 weeks of pregnancy.

Biochemical pregnancy usually requires no treatment and poses no significant harm to the body.

Is biochemical pregnancy common?

Yes.

Among all women who conceive, 30% experience biochemical pregnancy.

SYMPTOMS

What are the symptoms of a biochemical pregnancy?

The symptoms are similar to a delayed menstrual period, and many women experience a biochemical pregnancy without realizing it. Only women who have their blood hCG tested immediately after conception and later find that hCG fails to rise normally will be diagnosed by a doctor as having a biochemical pregnancy.

CAUSES

What are the causes of biochemical pregnancy?

Since specimens of biochemical pregnancy cannot be collected, the exact cause of biochemical pregnancy remains unknown.

It is generally believed that the causes of biochemical pregnancy are consistent with those of spontaneous abortion, which may be related to factors such as embryonic chromosomal abnormalities, luteal insufficiency, and viral infections. Among these, embryonic chromosomal abnormalities may be the primary cause.

DIAGNOSIS

Can a positive hCG in biochemical pregnancy indicate the presence of other diseases?

As we know, a positive hCG may indicate pregnancy, but the following conditions require caution:

• Ectopic pregnancy: Blood and urine hCG can be positive in women with an ectopic pregnancy, but transvaginal ultrasound can detect that the gestational sac is not in the uterus, confirming the diagnosis.

• Gestational trophoblastic disease: If hCG remains at high levels after four months of pregnancy, conditions such as choriocarcinoma or invasive hydatidiform mole should be suspected.

• Pituitary hCG secretion: Normally, the pituitary gland secretes very small amounts of hCG, but in some individuals, the secretion is relatively high, leading to elevated hCG levels in the blood. If low levels of hCG persist and gestational trophoblastic disease is ruled out, excessive pituitary hCG secretion should be considered. Oral contraceptives for three weeks can help suppress hCG secretion.

• Tumor-secreted hCG: Besides gestational trophoblastic tumors, other cancers such as testicular cancer, bladder cancer, uterine cancer, lung cancer, liver cancer, pancreatic cancer, and stomach cancer can also secrete hCG. In these cases, hCG typically remains at low levels, unlike the rapid doubling seen in early pregnancy.

• False-positive hCG: This may occur due to testing errors or artificial hCG injections.

TREATMENT

Which department should I visit for a biochemical pregnancy?

Gynecology, Obstetrics and Gynecology.

Does a biochemical pregnancy require treatment?

Usually no treatment is needed. In fact, many biochemical pregnancies occur unknowingly and do not cause any harm to the body.

DIET & LIFESTYLE

What should patients with biochemical pregnancy pay attention to in their diet?

No special precautions are needed. Eat as usual without avoiding cold, spicy, or stimulating foods. There is no need for specific "tonic foods," and random purchase of health supplements is not recommended.

What should patients with biochemical pregnancy pay attention to in daily life?

No special precautions are required. Like any other woman, maintain genital hygiene, follow a regular routine, and exercise regularly.

PREVENTION

How to Prevent Biochemical Pregnancy?

Biochemical pregnancy is usually caused by congenital issues such as embryonic chromosomal abnormalities and is a natural elimination process, so there is no need to prevent it.

In fact, biochemical pregnancy often goes unnoticed because it lacks obvious clinical symptoms (except for delayed menstruation).