Covid-19 vaccines do not increase risk of miscarriage, foetal anomaly: KKH doctor cites study in response to letter

SINGAPORE - There is no evidence of increased risks for mothers-to-be who take a Covid-19 vaccine, said experts.

Data from nearly 4,000 pregnant women in the United States showed there was no greater risk of miscarriage, foetal anomaly or pre-term labour, said Professor Tan Hak Koon from KK Women's and Children's Hospital (KKH).

Prof Tan, who is chairman of the hospital's division of obstetrics and gynaecology, spoke to The Straits Times after concerns were raised by five parents who wrote a letter to KKH last week.

The letter, which circulated in online chat groups, asked for evidence on vaccine safety from controlled clinical trials. Among other things, it said that "of particular concern" were the risks of miscarriages and birth defects.

The study Prof Tan cited looked at 3,958 pregnant women who were vaccinated from Dec 14 last year to Feb 28. Fifty-four per cent received the Pfizer-BioNTech jab, while the rest had the Moderna one.

The study was peer-reviewed and published in the highly regarded New England Journal of Medicine in April. Its findings indicate that there are no higher risks of adverse outcomes to mothers and their babies, and that the vaccine is safe to take at any point in pregnancy.

Prof Tan said that to assess whether the risks could be higher, comparison needs to be made with the baseline risk. The background risk for foetal anomaly is about 3 per cent to 3.5 per cent, he noted. For miscarriage, it is about 15 per cent, and for pre-term labour, it is 8 per cent to 12 per cent.

A pre-term birth refers to the birth of a baby before 37 weeks.

In the study, the rate of foetal anomaly reported was 2.6 per cent, Prof Tan said. For miscarriage, it was 13.5 per cent, and for pre-term labour, it was 8.6 per cent.

He said: "All these fall within the normal background risk."

He said that since the official launch on June 14 of vaccination for pregnant women at KKH, more than 80 bookings have been made with the hospital, which is an "encouraging" response.

Those who are pregnant have since June 4 been able to register for Covid-19 vaccination under the national programme. They were previously advised to hold off until more information was available.

The Ministry of Health (MOH) said on May 31 that the Expert Committee on Covid-19 Vaccination had reviewed data as inoculation was rolled out to pregnant women globally, and found no evidence to suggest that the Pfizer-BioNTech or Moderna shots could cause harm.

However, as the amount of data collected from this population segment is still much smaller compared with that from the general population, the ministry advised mothers-to-be to discuss the matter with their doctors.

MOH said the vaccine was safe for women who were breastfeeding, with no need to suspend it if they wanted to get the jab.

Prof Tan said that the risk of vaccination has to be considered against that of getting Covid-19.

"Because of physiological changes during pregnancy, pregnant women are less able to tolerate any respiratory infection, not just Covid-19, but also flu and pneumonia, for instance," he said.

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The College of Obstetricians and Gynaecologists Singapore and the Obstetrical and Gynaecological Society of Singapore told ST in a joint statement last Friday (June 18) that there is published data showing that pregnant women who become infected with Covid-19 are at higher risk of developing severe illness.

They are thus more likely to require admission to an intensive care unit, mechanical ventilation and oxygen treatment.

The babies may also need to be delivered early to help the mothers' heart and lung functions.

"This means that symptomatic Covid-19 pregnant women are twice more likely to have pre-term births, and their babies are also more likely to need admission to the neonatal intensive care unit," the joint statement said.

It added that while there are to date no published clinical trials of Covid-19 vaccines that included pregnant women, Pfizer and BioNTech had completed a developmental and reproductive toxicity study that showed no evidence of fertility or reproductive toxicity in animals.

An MP for Sengkang GRC, Ms He Ting Ru, who gave birth last December and had her first Covid-19 jab last week, said she had been concerned over whether it was safe for her youngest son, who is fully breastfed, if she took the vaccine.

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With the revised guidelines from MOH for pregnant and breastfeeding mums, she consulted her doctor, who gave her the go-ahead.

"There is a lot of misinformation out there, but we are facing a serious pandemic and should do our part to protect segments of the population by getting vaccinated if we are able to," said the mother of three.

A total of 38,590 babies were born in Singapore last year.

This article was first published in The Straits Times. Permission required for reproduction.