Guide to Vaccines Before and During Pregnancy

Pregnancy is a time of joy and anticipation, but it is also a time for precautions and preparation. Pregnancy vaccines are an essential precaution; they protect mother, fetus, and baby from dangerous diseases.

Pregnancy is a delicate, vulnerable time when immunity is reduced and illnesses can be severe. Several conditions are more serious when they occur at this time. Some infections are doubly dangerous — they make you ill and also affect the baby.

Why are Diseases Dangerous in Pregnancy?

The job of the immune system is to keep the body safe from invaders. To this end, it attacks anything it sees as foreign.

This includes the fetus in the womb.

To keep the fetus safe, Mother Nature suppresses the immune system at this time. Obviously, this creates vulnerability to infections. Cell-mediated immunity, crucial to protection against viruses, is significantly reduced.

What are the Dangers?

Diseases are dangerous in several different ways during pregnancy. The reduced immunity makes some diseases, like influenza, chickenpox, and Covid-19 (SARS-CoV-2), more severe in pregnant women. There is a much higher risk of progression to severe pneumonia, hospitalization, and intensive care.

Some infections like chlamydia, cytomegalovirus, hepatitis, influenza, rubella, syphilis, and toxoplasma, cross the placenta to infect the baby. These diseases can cause abortions, premature birth, or birth anomalies.

Why are Some Vaccines Advised Before Pregnancy?

Not all vaccines are appropriate during pregnancy. You should take some of them when you are planning to start a family, before you are pregnant.

There are different reasons:

• The vaccines need multiple doses and several months to provide protection, like hepatitis B.
• The vaccines are dangerous or of unproven safety to mother and baby during pregnancy.
• Some vaccines provide long-term or lifelong protection. It’s just prudent to take them before pregnancy.
• Some vaccines, like the yellow fever vaccine, generate an inadequate immune response during pregnancy.

Rubella (German measles)

Rubella itself is a very mild illness, and the low fever and short-lived rash often go unnoticed. The disease, even if diagnosed, has no specific treatment.

The rubella virus crosses the placenta and affects the baby. This is what makes it so dangerous during pregnancy.

The earlier in pregnancy this happens, the worse it is for the baby. Rubella in pregnancy can lead to miscarriage, fetal death, or congenital rubella syndrome (CRS).

CRS consists of multiple defects, particularly of the heart, brain, eyes, and ears. Before the rubella vaccine, CRS was a common cause of mental retardation, deafness, and visual disability.

Hepatitis B

Many viruses infect the liver and cause liver disease, but five viruses have an affinity for this organ. They are named the hepatitis A, B, C, D, and E viruses. All of them cause acute hepatitis, an immediate, short disease.

The B, C, and D hepatitis viruses also cause smoldering, long-term disease. They gradually destroy the liver cells and structure, causing jaundice and other signs months to years after the initial infection. These viruses also cause liver cirrhosis and cancer.

The age at infection determines the outcome. Children over five (and adults) are able to clear the virus from the body, and only about 5% will have chronic hepatitis. But if babies get the infection, before or during birth, the virus persists in almost all of them. Most adults who develop hepatitis B associated liver disease acquired the infection in childhood.

Infection acquired from the mother before or during birth is known as vertical transmission. It is essential to stop it by ensuring you don’t get hepatitis B during pregnancy.

Chicken Pox

Also known as varicella, this is an exceptionally infectious viral disease. During pregnancy, it’s bad for both mother and baby. Premature delivery happens sometimes; low birth weight is common.

The serious conditions associated with chickenpox in pregnancy are:

• Congenital varicella syndrome.
• Neonatal chickenpox.
• Maternal varicella pneumonia.

Congenital varicella syndrome. It consists of defects of the skin, brain, limbs, bowel, eyes, intestines, urinary system, and heart. About 30% of these unfortunate babies die in the first few months. Herpes zoster, developmental delay, and learning disabilities are common.

Neonatal chickenpox. Chickenpox in a newborn baby is very dangerous, and happens if the mother gets infected shortly before delivery. This condition has a high mortality.

Varicella pneumonia. Chickenpox is usually a mild disease in children. However, it is often severe in teenagers and adults. Pregnant women are at high risk for serious disease, including varicella pneumonia, a dangerous condition.

Influenza (the flu)

Influenza is very dangerous during pregnancy. Women have a high risk of severe disease, hospitalization, respiratory failure, and death. For the baby, the bad outcomes include miscarriage, premature birth, low birth weight, stillbirth, and birth defects.

The influenza virus changes frequently, and we need a new vaccine every year. The newly formulated vaccine is released before peak transmission season every year. That’s when you should take it, before pregnancy or during it.

Two types of influenza vaccine are available, live and inactivated. During pregnancy, you should only take the inactivated (killed) vaccine. Before you are pregnant, you can take either. If you do get the live vaccine, avoid conceiving for a month. The inactivated vaccine is an intramuscular injection; the live vaccine is sprayed into the nose.

The antibodies generated by the influenza vaccine cross the placenta and protect the baby for the first six months of life. This is valuable because the influenza vaccine is only given to children after six months. You should take the influenza vaccine at least two weeks before delivery to allow enough time for antibody formation and transfer.

Whooping Cough (Pertussis)

A cough doesn’t sound scary. However, whooping cough is dangerous for newborns and young babies. At this young age, pneumonia, bleeding into the brain, and feeding difficulties are frequent, leading to hospitalization, and even death.

The best way to protect your baby is to have the vaccine during pregnancy. The antibodies produced by your immune system will pass through the placenta and protect your baby during the first few months.

The antibodies to pertussis do not last long, so it’s best to take the vaccine late in pregnancy. The high levels of antibodies just after vaccination will be of great benefit. On the other hand, if you take the pertussis vaccine before pregnancy, the antibodies will have declined to low levels by the time you get pregnant.

The pertussis vaccine is only available combined with the tetanus and diphtheria vaccines. Since tetanus is also one of the vaccines recommended for pregnant women, this makes administration easy.

Tetanus

Tetanus is a bacterial disease. Tetanus of the newborn, tetanus neonatorum, is a deadly disease and caused thousands of deaths around the world. Unsanitary birthing conditions and traditions facilitate tetanus in babies.

Since the tetanus vaccine was adopted worldwide, this deadly disease is rare. However, you must still take the vaccine during pregnancy to protect yourself and your baby.

The tetanus toxoid (vaccine) is available by itself, but is usually given as a combination with diphtheria toxoid and acellular pertussis vaccine. The vaccine is safe, and generates a good immune response which is transferred across the placenta to protect your baby, too.

Other Vaccines for Specific Regions and Situations

Some vaccines are advised in pregnancy, but only to people living in or traveling to places where there is high risk of specific disease.

Cholera. A dangerous, life-threatening diarrheal disease. Women living in affeced areas should receive this vaccine. The inactivated (injectable) vaccine is considered safe in pregnancy. The oral (live) vaccine has also been used in pregnant women, with no significant adverse effects.

Ebola. A hemorrhagic viral fever with a high death rate. The vaccine is a live viral vector, but engineered so that it cannot replicate. Probably safe in pregnancy, and protects against a deadly infection.

Encephalitis, tick-borne. Inactivated vaccine. Should be given to pregnant women in areas where it is prevalent.

Hemophilus influenza b. A childhood vaccine it is recommended for pregnant women with disorders of immunity. Congenital immunodeficiency, AIDS, blood cancers, absence of the spleen, transplant recipients, and sickle cell disease are some of the conditions in which this vaccine is given during pregnancy.

Hepatitis E. This vaccine is used to control outbreaks, and should be given to pregnant women. Recombinant vaccine, very safe.

Meningitis. Women living in regions where meningitis is common should receive the meningitis vaccine.

Rabies. A fatal disease with no dependable treatment. The vaccine course must be given to pregnant women after suspect animal bites. Currently used rabies vaccines and immunoglobulins are safe.

Yellow fever. This is a live viral vaccine, and should be used with caution. If not essential, pregnant women should avoid travel to areas where yellow fever is common. If unavoidable, the vaccine is best taken before pregnancy or in the first half of pregnancy. The immune response to this vaccine is poor in the later part of pregnancy.

Breastfeeding women should not take the yellow fever vaccine. The vaccine virus passes through breast milk and is known to (rarely) cause encephalitis in babies.

Are Vaccines Effective in Pregnancy?

Pregnancy dampens the immune system to protect the fetus. This suppression also affects the response to vaccination.

Yellow fever vaccine, for example, generates very poor immunization during pregnancy, especially if the vaccine is given in the last three months.

Responses to the diphtheria and tetanus toxoids, as well as to the acellular pertussis antigens, seem good during pregnancy. Antibody levels are adequate, though cellular immune responses are poor.

What is the Right Time for Vaccination in Pregnancy?

The first eight weeks of pregnancy are when a baby’s organs are being formed. This is when there is the highest risk of any disease, drug, or other influence causing birth defects. In general, you should avoid vaccines during this period.

The second half of pregnancy is a good time for taking any vaccine. The risk of birth defects is now low, and there is adequate time for the formation of antibodies and their transfer to the baby.

Giving pregnancy vaccines in the ninth month has the advantage of high maternal antibody levels and transfer of large amounts of protective antibodies to the baby. However, if the baby is born a few weeks early, there may be no protection. Weeks 27 to 30 are probably optimal.

Are Vaccines Safe During Pregnancy?

Yes, most vaccines are.

Killed/inactivated viral and bacterial vaccines are safe.

Vaccines that have only components of the disease-causing organisms are safe. The hepatitis B, tetanus toxoid, and the acellular pertussis vaccines are such vaccines.

Live viral vaccines are made by weakening the disease-causing virus. These viruses set up an infection and stimulate your immune system, without causing significant illness.

These live vaccines should not be given during pregnancy, as the viruses can cross the placenta and infect the baby.

Accidental Vaccination

What if you take a vaccine by mistake during pregnancy, or before you know you are pregnant? Or if you take a vaccine and get pregnant soon after?

These are frequent occurrences and were much feared. Women were scared, as were their doctors, and pregnancies were sometimes ended over fears of having an abnormal baby.

Such fears are based on missing data. Studies of vaccine safety and efficacy do not include pregnant women as there is a risk of the live organism crossing the placenta and infecting the fetus. Thus, positive evidence of the safety of vaccines in pregnancy is lacking.

Conclusion

Vaccination during pregnancy is safe, effective, and vital. Some vaccines are not suitable for use in pregnancy, but your doctor knows about them. If your doctor recommends a vaccine, you can be sure it is safe for you and the little human inside you.

Vaccination is a major component of the strategy to make pregnancy safe and reduce the death rate among babies and infants. Today, deadly situations like tetanus neonatorum and newborn varicella are almost never seen. By getting vaccinated, you give your baby the gifts of antibodies, immunity, and safety.

References

Maurizio de Martino. Dismantling the Taboo against Vaccines in Pregnancy.

Mala Arora and Rama Lakshmi. Maternal vaccines safety in pregnancy.

Aneta S Nitsch-Osuch et al. Influenza vaccination in pregnancy – current data on safety and effectiveness.