What You Should Know About Whooping Cough (Pertussis) and Pregnancy

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Probably, you have heard a lot about whooping cough –also known as pertussis—as a childhood infectious disease that is extremely dangerous, yet completely preventable through vaccination, and that the vaccine is on the regular pediatric vaccination schedule. Known as DTaP, the vaccine given to babies and children below age 7 is indeed exquisitely important as a preventive measure against pertussis as well as diphtheria and tetanus. But you may have heard less about pertussis in adults, including pregnant women, and the adult version of the vaccine, called Tdap, which you should receive during every pregnancy. So today let’s focus on pertussis in connection with the mother.

Pertussis, whooping cough, is caused species of bacteria called Bordetella pertussis, which attaches to small, hair-like extensions structures called cilia, which line upper airways. Back in the 19th and early 20th centuries, pertussis was one of a handful of infectious diseases that killed many children, especially in crowded cities with a lot of immigrants. This changed dramatically with the advent of the pertussis vaccine that today is combined with vaccines for tetanus and diphtheria (Tdap for adults, DTaP for young children). In poor countries, however, vaccination rates are low. Furthermore, in certain communities in wealthy countries, misunderstanding combined with misinformation spread by anti-vaccine activists has led to a lapse in vaccination rates, which potentially can be very dangerous. In the United States, this is part of the reason why only approximately half of pregnant women have received the Tdap vaccine, or an up-to-date booster.

Often, doctors make a clinical diagnosis of whooping cough, meaning that a presumptive diagnosis is made based on the fact that you have not received a Tdap vaccine booster recently enough to maintain adequate immunity (or you were never vaccinated) and you develop a characteristic whooping cough that comes in intense episodes. A complete blood count (CBC) showing elevated white blood cell count (WBC) would indicate that your body is fighting an infection, which would support the diagnosis, but a definitive diagnosis can be made by swabbing your nose or throat and culturing the sample in the laboratory to see if B. pertussis grows. Along the way, you should have a chest X-ray to rule out pneumonia, which can develop as a complication.

Pertussis cause what’s called paroxysmal symptoms, meaning symptoms that come in intense episodes. These episodes feature a productive cough (a cough that brings up phlegm), which is so intense that often the person produces whooping sound while inhaling sharply to take in air between coughs; this why it is called “whooping cough”. Such a cough can interfere with your daily activities, including getting a good night’s sleep. Intense coughing also can trigger vomiting (which can cause electrolyte disturbances), and, if you have stress urinary incontinence (difficulty holding in urine when pressure increases in the pelvis, which is very common among pregnant women), the coughing can cause urine leakage. Along with, or in the days prior to the whooping cough, are common cold symptoms, such as runny nose, watery eyes, sneezing, fatigue, and low-grade fever. Pertussis also can be complicated by dehydration, ear infection, and pneumonia.

The main danger maternal pertussis scenario for a baby is when the mother suffers from pertussis after the baby has already been born. This can happen when the mother develops whooping cough near the end of pregnancy, or after delivering. Pertussis causes severe respiratory disease in infants that is potentially fatal, and approximately 70 percent of such cases are the result of unvaccinated mothers.

Antibiotic therapy against B. pertussis consists of medication from a family of antibiotics known as macrolides, which include azithromycin, erythromycin, and clarithromycin. There is some concern about clarithromycin in pregnancy based showing harmful effects in the fetus in laboratory animals, and little is known about the pregnancy risk of a newer macrolide called fidaxomicin. Thus, azithromycin and erythromycin are the best choices. Although these antibiotics do not moderate the whooping cough attacks, or shorten the duration of the disease, they do stop the B. pertussis bacteria from spreading through the body and they also prevent secondary infections (infections from other organisms). Generally, the medications are considered safe in nursing mothers, since only tiny amounts actually enter breast milk.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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