Maternal Health

The Maternal Health sub-topic explores evidence of the benefit of immunization to the health of women during pregnancy, to their unborn and newborn child, as well as improvements to maternal & child health outcomes.

5 Key Concepts

Key Evidence: Pregnant women in Bangladesh who received the influenza vaccine had elevated levels of anti-influenza antibody in their breastmilk. The infants of mothers who received the vaccine during pregnancy had fewer episodes of respiratory illness with fever than the infants of mothers who did not receive the influenza vaccine during pregnancy. Further, exclusive breastfeeding was found to have a protective effect against respiratory illness with fever in infants.

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Key Evidence: The breastmilk of mothers in Bangladesh who received the meningococcal vaccine during pregnancy had anti-meningococcal antibody levels at 3-6 months after delivery of four to five times higher than that of mothers who did not receive the vaccine.

From the VoICE Editors: Although this study was published in 2002, the data on this topic are sparse as it is methodologically difficult to conduct studies to evaluate the relationship between anti-meningococcal antibodies in breastmilk and protection.

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Key Evidence: Through use of local Maternal Child Health (MCH) incentives, along with the use of locally appointed Health Activists, India's National Rural Health Mission (NRHM) multiple-strategy community intervention program was able to achieve household level improvements reflected as an increase in all of the following indicators for women and children over the 7 year program:
- the proportion of pregnant women having 3 or more ante-natal check-ups (from 43% to 74.5%)
- those receiving at least one Tetanus Toxoid injection (from 83.5% to 93.6%)
- institutional deliveries (from 35.7% to 77%)
- post-natal check-ups within 2 weeks of delivery (from 49% to 67.2%) and
- children who received ORS for diarrhea from (32.3% to 44.8%).

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Key Evidence: Mothers who had skilled birth attendance and post-natal care were approximately 6 times were likely to have fully immunized children.

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Key Evidence: Mothers infected with rubella virus during the first trimester of pregnancy can give birth to children with permanent disabilities such as intellectual impairment, autism, blindness, deafness, and cardiac defects. The infection is completely preventable if mothers are vaccinated before pregnancy.

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Key Evidence: During the 2009 UK influenza A H1N1 pandemic, pregnant women who contracted influenza were five times more likely to have perinatal mortality (stillbirths) and three times more likely to have a preterm delivery, than were pregnant women who did not contract the virus.

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Key Evidence: Pregnant women have a nearly 2.5 times greater risk of being hospitalized with lab-confirmed influenza than non-pregnant women.

From the VoICE Editors: The WHO review did not find an elevated risk of more severe outcome in pregnant women compared to non-pregnant women. This may suggest that pregnant women are more likely to be hospitalized for influenza for precautionary reasons.  

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Key Evidence: Pregnant women are at particularly high risk of serious illness and death from a variety of bacterial and viral diseases, such as influenza, pneumococcal pneumonia, and Group B strep, for which vaccines exist or are in development. Vaccine-preventable diseases in pregnancy are associated with adverse pregnancy outcomes such as spontaneous abortion, congenital anomalies, preterm birth, and low birth weight.

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Key Evidence: Studies from multiple Western countries have found that pregnant women infected with influenza during the 2009 A/H1N1 pandemic were at higher risk of miscarriages, stillbirths, low birthweight and premature deliveries. The risk of fetal death was between 2 and 5.5 times higher in pregnant women with influenza than in pregnant women without influenza. In the UK, the rate of stillbirths was 4.5 times higher and the likelihood of preterm delivery was 4 times greater in influenza-infected pregnant women than non-infected women.

From the VoICE Editors: Although this article indicated that influenza vaccination is safely used for the mother and the fetus, conflicting data exists on the effect of vaccination in improving preterm birth rates. 

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Key Evidence: In Brazil, where pertussis cases have climbed, mainly in infants <4 months of age, vaccinating pregnant women with Tdap vaccine at the same coverage rate as influenza vaccination in pregnant women (57%) would reduce pertussis cases in children under 1 year of age by 41%, deaths by 43%, and would be cost-effective, according to the WHO thresholds.

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Key Evidence: In Japan, which has experienced a re-emergence of pertussis among adolescents and adults, vaccinating pregnant women with the Tdap vaccine would be cost effective in preventing the illness in young infants (<3 months of age) and in mothers, according to the WHO definition of cost effectiveness. This is true even if only 50% of pregnant women receive the vaccine.

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Key Evidence: Pertussis causes nearly 200,000 deaths in children worldwide, nearly all in infants too young to be vaccinated. Vaccinating pregnant women against pertussis with a single dose of Tdap vaccine would be 89% effective in protecting infants against the disease over their first 2 months of life and would reduce pertussis incidence in newborns in the U.S. by 68% (assuming 75% of mothers are vaccinated).

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Key Evidence: A study in Australia estimated that adding dTpa vaccination for pregnant women to the current pertussis immunization program for children would prevent an additional 8,800 symptomatic pertussis cases (mostly unreported) and 146 hospitalizations each year in all ages, including infants and their mothers, as well as one death every 22 months. The study found maternal pertussis vaccination to be cost-effective.

From the VoICE Editors: Note: The formulation used in this study is abbreviated dTpa.

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Key Evidence: A large study in California involving nearly 150,000 newborns found that vaccinating pregnant women with the Tdap vaccine provided 91% protection against pertussis infection among infants under 2 months of age and 88% protection before the infants had any vaccinations. The study also showed that vaccinating mothers during their pregnancy did not reduce the effectiveness of infant vaccination but that maternal Tdap vaccination provided additional protection to the infants through their first year of life.

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Key Evidence: In Argentina, more than 50% of deaths due to pertussis occurred in infants younger than 2 months of age -- too young to be vaccinated in the country. The impact of maternal pertussis vaccination in protecting their infants against the disease reduced the incidence of pertussis in infants less than 2 months old by half, when comparing states with high and low maternal vaccination rates.

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Key Evidence: Infants born to mothers who reported receiving influenza vaccination during pregnancy had a 64% lower risk of getting influenza-like illness in their first 6 months of life, a 70% lower risk of laboratory-confirmed influenza, and an 81% lower chance of being hospitalized with influenza than infants whose mothers did not report getting the influenza vaccine during pregnancy. Since influenza vaccines are not effective in children less than 6 months old, immunizing pregnant women against influenza is a public health priority.

From the VoICE Editors: Data is from a study spanning more than 8 years at a large healthcare organization in the Western U.S.

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Key Evidence: An analysis of data from three studies showed that the rates of severe pneumonia in infants in their first six months of life was 20% lower overall in infants whose mothers received the influenza vaccination during pregnancy than in infants whose mothers had not, and the rates of severe pneumonia was 56% lower during periods when influenza circulation was highest. These findings correspond with evidence that influenza infection predisposes individuals to pneumococcal infection.

From the VoICE Editors: The incidence rate of severe pneumonia in the vaccine group compared to the control group was 43% lower in South Africa, 31% lower in Nepal, but not significantly different in Mali.

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Key Evidence: Vaccinating women during their second or third trimester of pregnancy with the Tdap vaccine was 81% effective in preventing pertussis in their infants in the first two months of life, according to a case-control study in Argentina.

From the VoICE Editors: This is one of the first studies to measure the effectiveness of maternal pertussis vaccination in a middle-income country and its findings support Argentina's decision to introduce the vaccine.

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Key Evidence: The period following delivery but before an infant acquires immunity to diseases by natural exposure or immunization -- is when infant mortality from infections is highest. Vaccinating pregnant women has shown to be effective in protecting young infants against influenza and pertussis.

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Key Evidence: Despite the introduction of pneumococcal conjugate vaccine (PCV) in the childhood immunization program in New Zealand, the incidence of invasive pneumococcal disease in neonates (<30 days old) remains relatively high at 6 per 100,000 (versus 2/100,000 in the U.S.). Out of 19 cases in infants <30 days old in this study, 9 (47%) occurred during the first 7 days of life and 6 within the first 48 hours. If proven effective, maternal vaccination would cover 74% to 84% of the serotypes that infected these infants, depending on the vaccine.

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Key Evidence: Immunization against tetanus, pertussis and influenza during pregnancy has been shown to have a profound effect on the health of the mother and fetus, and increases survival of infants in their first months of life. Maternal immunizations with tetanus toxoid-containing vaccines has been one of the main contributors to the 94% reduction in global deaths due to tetanus since 1988. Between the 1970s to the early 2000s, maternal immunization against pertussis brought disease incidence down to 5,000 cases per year from the earlier 100,000-250,000 cases per year in the United States. Vaccination of mothers for influenza has brought down confirmed cases of the disease by 63%.

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Key Evidence: Vaccinating pregnant women against pertussis at least one week before delivery was found to be 91% effective in preventing the disease in infants <3 months old and 95% effective in preventing infant deaths in a study conducted in England over a 3-year period following the introduction of dTap-IPV vaccine for pregnant women. Of the 37 deaths from pertussis in infants that occurred in England from 2009 to 2015, 32 (86%) were in infants <2 months of age, highlighting the vulnerability of very young infants to severe pertussis. All but 2 of the deaths in <2 month olds were in children whose mothers hadn't been vaccinated against pertussis during their pregnancy, while in the 2 other cases, the vaccination occurred too late in the pregnancy (<10 days before the birth).

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Key Evidence: An study using GIS to quantify the percent of pregnant women in Mozambique without access to tetanus toxoid (TT) vaccine at varying distances from health facilities estimated that if women cannot travel more than 5 km to a TT immunization site there will be almost 18,000 neonatal tetanus cases each year that could be prevented, costing the country more than US$362 million in treatment costs and lost productivity. Covering 99% of women with TT will currently require people to travel up to 35 km to obtain an immunization.

From the VoICE Editors: GIS, a geospatial information system, is a computer system capable of capturing, storing, analyzing, and displaying geographically referenced information.

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Key Evidence: In a case-control study in the state of São Paulo, Brazil, vaccination of pregnant women with Tdap vaccine was 83% effective in preventing pertussis in their infants less than 2 months of age -- before their first dose of DPT -- and 81% effective after controlling for household income and mother's age.

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Key Evidence: Infants less than 2 months old are too young to be vaccinated against pertussis yet are at highest risk of severe disease - - a 75% hospitalization rate and a 1% case fatality rate. A case-control study in six U.S. states found that vaccinating women during the third trimester of pregnancy with Tdap vaccine provided 81% protection against pertussis to infants <2 months and 91% protection against hospitalized cases of pertussis.

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