Vaccines while pregnant
After growing up in Walnut Creek and completing my Ob/Gyn residency at UCSF-Fresno, I joined Dr Leach’s practice in 2015. To complement Dr. Leach’s column ‘Menopause Matters’ I plan to review common questions I hear from pregnant women, and other aspects of women’s health care.
Vaccines have been a hot topic in recent years. In the United States we have seen several outbreaks of diseases which we have vaccines for: whooping cough, measles, and mumps. Pregnant women every year ask their doctors: Should I really get a vaccine now? Why?
Though most vaccines are not given to pregnant women, two vaccines are recommended during pregnancy: the influenza (flu) and Tdap vaccines. Below I will review vaccine basics, and why they are recommended in pregnancy.
A quick review: Vaccines
Vaccines are made from weakened or inactivated parts of bacteria and viruses which cause infectious disease. Vaccines are most effective when given before exposure to a disease, and can either prevent the disease entirely, or result in a less severe form. Vaccines have helped slow or stop diseases like smallpox, polio, and the chicken pox. Scientists today are working to develop vaccines against other diseases like HIV and Zika. When a vaccine is given it causes the body to create protective proteins called antibodies. These antibodies are ready to fight off that disease if you should ever be exposed again. It takes about 2 weeks after getting a vaccine before your body has produced enough antibodies to protect from infection.
Tdap is a vaccine against tetanus, diphtheria, and pertussis (whooping cough). Whooping cough is a respiratory infection which may cause only mild symptoms, but can be especially dangerous for newborns and young children. Most adults received a whooping cough vaccine in childhood, but the protection provided decreases over time. So many adults may no longer be immune.
Children receive their first whooping cough vaccine at 8 weeks old. Before then they only have protection if they receive protective antibodies from their mother. California had 4,750 cases of whooping cough in 2015, and ⅔ of the patients hospitalized were infants younger than 4 months. Every year as many as 20 babies die in the US from whooping cough.
When a woman receives a Tdap vaccine during pregnancy, her body increases production of protective antibodies. These antibodies are transmitted to the baby until delivery, and can be passed to her newborn when breastfeeding. If a woman gets the Tdap vaccine during her third trimester (27-36 wks) her baby’s risk of whooping cough in the first 8 weeks of life is decreased by at least 85%. A Tdap vaccine is recommended every pregnancy.
The Flu Vaccine
Flu season lasts from October to May each year, and every year a new flu vaccine is produced. Influenza is usually a mild respiratory disease, and may cause cough, fever, body aches and occasionally vomiting or diarrhea. Pregnant women are at higher risk of serious complications from the flu than most other adults. Complications include pneumonia, respiratory failure requiring breathing support (intubation), and even death. During the H1N1 influenza epidemic 12% of all US deaths during pregnancy were caused by the flu. Fever caused by the flu in early pregnancy increases the risk of birth defects. Pregnant women with the flu are at increased risk of early delivery.
Large studies have shown no increased risk of birth defects or other problems in babies born to women who received the flu vaccine during pregnancy. And just like with the Tdap vaccine, women who receive the flu vaccine during pregnancy will pass some protection onto their babies after delivery.
While vaccines are generally safe, anyone with a previous serious allergic reaction to a vaccine or its’ components should not be vaccinated. The nasal flu vaccine (spray) is a live virus, and should not be given during pregnancy.