What you will receive
The inoculation booster the report describes as “not a potential health risk,” is supposed to help protect women at greater risk of becoming pregnant.
Ontario will provide the boosters for women between the ages of 30 and 45 who have had non-hormonal post-menopausal treatments for at least three years. These include hormone therapy or moderate-intensity hormone replacement therapy, as well as endometriosis, uterine fibroids and endometrial cancer.
The researchers note that these health factors are not specified in Ontario’s Health Information Act, so it is not clear how common women who have undergone such treatments are to become pregnant, or whether there is an age limit for accessing the booster.
The researchers note that if a woman has given birth within the past 20 years, she is at low risk of becoming pregnant without a booster jab.
Why it’s an issue
The Canadian Medical Association Journal report suggests a link between the booster vaccine and an increased risk of miscarriage, preterm birth and stillbirth. Women who have had the booster injection are 3.8 times more likely to miscarry if they are experiencing IVF treatments that have failed to produce a pregnancy, according to one study. The booster vaccination is an option for women who have had unsuccessful IVF treatments, and those who have undergone anti-hormonal treatment to treat secondary peri-menopausal symptoms, the report states.
Some researchers have proposed that the booster injections could unintentionally cause infertility in women who had failed to conceive naturally, by inducing periods early or through sexual stimulation.
It is important to note that there is no evidence that the booster injection should be discouraged for women with endometriosis, polycystic ovary syndrome, uterine fibroids or cancer of the uterus, the report states.
In the report, the CMAJ recommends that the vaccination be offered to women who have a family history of infertility or who have had IVF treatments that have failed to produce a pregnancy.
The team, which included Dr. Susan Chiro (now a family physician in California) and Richard Lin (now an associate professor at the University of Toronto, in her division of obstetrics and gynecology), say they do not intend to discourage breastfeeding, and women who need the booster to continue breast feeding should consult their health care provider about the best course of action.
The report does not set out to say if the booster shots increase the risk of miscarriage, preterm birth and stillbirth. It should be noted that no link has been established. However, the CMAJ does state that the data and evidence are not sufficient to decide whether the booster shot should be offered for women who have experienced in vitro fertilization.
Though the study says, in general, that most women who have had the booster injection will not need additional follow-up, an additional booster injection would be recommended for women who received previous booster injections. It is suggested that women with uterine fibroids or polycystic ovary syndrome be offered two booster injections.
When can I get it?
Most women who have had the booster injection should begin to receive boosters four to six weeks after the injection, the report states. However, if women have had IVF treatments, and reported higher rates of pregnancy, they are advised to get a booster injection four to six weeks before their last implantation of the embryo.
In Ontario, only women with at least one child should be offered boosters.
Canada has far more women who have had a baby than the United States. As of 2013, there were 541,000 children being raised by their parents in Canada, according to Statistics Canada.
The American Association of Reproductive Medicine does not recommend pregnant women receive boosters. The American Society for Reproductive Medicine has different advice — for both women and physicians — but not specifically on the question of booster shots.