Why Does Miscarriage Happen Even if the Pregnancy Scan Looks Normal?

1️⃣ Chromosomal or Genetic Issues

The most common cause of early miscarriage is a genetic or chromosomal abnormality in the baby.
This means something went wrong during fertilization, leading to abnormal cell division.

Even though the scan looks fine initially, the baby may stop developing later when the chromosomes fail to support growth.
This happens naturally and isn’t caused by the mother’s activities or habits.

Fact: More than 60% of first-trimester miscarriages occur due to genetic causes.

2️⃣ Incompetent Cervix (Cervical Insufficiency)

Sometimes, the cervix (the lower opening of the uterus) becomes weak and opens prematurely — usually in the 4th or 5th month of pregnancy.

This condition, called incompetent cervix, can cause miscarriage without pain or bleeding initially.
A woman might only feel pressure or mild discomfort.

Doctors diagnose this through a transvaginal ultrasound and prevent it by placing a cervical stitch (cerclage) around 12–14 weeks in future pregnancies.

3️⃣ Hormonal Imbalance

A sudden drop in the hormone progesterone, which supports the pregnancy, can lead to miscarriage even after a good scan.
Progesterone helps maintain the uterine lining and supports the embryo’s attachment.

Low levels can cause the uterus to contract or the lining to thin, leading to pregnancy loss.
That’s why women with a history of miscarriage are often given hormonal supplements during early weeks.

4️⃣ Maternal Health Conditions

Several underlying health conditions may not affect early scans but can interfere later.
Common examples include:

• Thyroid imbalance (hypo/hyperthyroidism)
• Uncontrolled diabetes or PCOS
• High blood pressure or preeclampsia
• Autoimmune diseases (like lupus or antiphospholipid syndrome)

Such conditions can affect blood flow to the baby or cause early placental problems.

Tip: Regular health check-ups and early medical management can significantly lower miscarriage risk.

5️⃣ Infections

Infections like TORCH (Toxoplasmosis, Rubella, Cytomegalovirus, Herpes) or urinary infections can silently affect the pregnancy.

A mother might feel completely normal, but these infections can interfere with fetal growth or damage placental function.

Simple blood tests can detect these infections, and timely treatment ensures a healthy next pregnancy.

6️⃣ Placental Problems

The placenta is the baby’s lifeline — it supplies oxygen and nutrients.
If it doesn’t form properly or detaches too soon (placental abruption), the baby can lose support suddenly.

Even if previous scans were normal, abrupt detachment or reduced blood flow can cause miscarriage at any stage.
This is one reason follow-up scans are vital through all trimesters.

7️⃣ Blood Clotting Disorders (Thrombophilia)

Some women have a natural tendency for blood clots to form easily.
When this happens inside the placenta, it blocks the baby’s oxygen and nutrition supply.

A test called the Thrombophilia Profile can detect this condition.
Treatment includes mild blood thinners (under a doctor’s guidance) to ensure healthy placental circulation.