About 19 percent of the Chinese women at childbearing age have thyroid diseases of various kinds before pregnancy, which increases the risk of infertility or miscarriage, a senior specialist warned.

Professor Teng Weiping of the Chinese Society of Endocrinology made remarks at an awareness raising event held by the society and people.cn.

As the top decision makers further relaxed family planning policy by allowing all Chinese couples to have two children, more women in their 30s or 40s began seeking to have a second child.

"They are at greater risk of pregnancy related hypothyroidism compared with younger mothers," Teng said.

Thyroid disease in pregnancy can affect the health of the mother as well as the child before and after delivery.

Hypothyroidism, wherein the thyroid gland produces an inadequate amount of thyroid hormones, is a common disorder particularly in women of childbearing age.

Hypothyroidism of the mother during pregnancy may result in developmental delays in the child.

Also, in some pregnant women with the condition, the possibility of miscarriage is nine times higher than in healthy counterparts, he said.

Major symptoms include fatigue and weight gain, which might be easily confused with that usually seen during pregnancy.

Teng, in response, recommended women go through screening for thyroid diseases before getting pregnant.

Experts said that China has more than 200 million people suffering from various kinds of thyroid diseases on the mainland.

The prevalence of thyroid diseases has risen sharply on the mainland in recent years, but public awareness remains relatively low, Teng said.