Zika Virus and Pregnancy: What You Need to Know

Published on: November 06, 2017

By now, we’ve all heard about Zika. What is it, and what does its presence mean? Bumps and Babies takes a closer look at the current evidence-based health advice for women who are pregnant or contemplating pregnancy in a Zika-affected area.

By Emma McNerlin


With worrying reports of the cluster of 1,400 cases of Zika-related microcephaly (small heads) in newborns in Brazil and the spread of the virus throughout countries of Southeast Asia, it’s no wonder that pregnant women in Bangkok are deeply concerned about the impact of the presence of Zika in the city and the health of their unborn babies. At the time of going to press, the Thai Ministry of Health had confirmed two cases in Thailand of microcephaly directly related to Zika infection.

This month’s Bumps and Babies article takes a closer look at the current evidence-based health advice for women who are pregnant or contemplating pregnancy in a Zika-affected area.

What is Zika virus

Zika is a Flavivirus from the same family as dengue fever, chikungunya and yellow fever. It was first discovered in the Zika jungle of Uganda in the late 1940s and has since migrated through Africa to Asia, and, more recently, to South America. Two distinct strains were identified in 2007: an African strain and an Asian strain, the latter of which has been identified in the recent outbreak in Brazil (World Health Organization [WHO], 2016).

Zika was first reported in Thailand in 2012, with only a handful of cases reported per annum until this year, which has seen a marked increase with 392 reported since January 2016 (Reuters Press Agency, 3 Oct 2016: figures correct at time of going to press).

How is Zika transmitted

Dengue fever, Chikungunya virus and Zika virus are spread by the bite of an infected Aedes mosquito. (Photo by Universal History Archive/UIG via Getty images)

Zika is carried and transmitted from bites by the female Aedes Mosquito (see photo). Contrary to popular belief, this Aedes Egypti mosquito in Thailand bites throughout the day, not only at dawn and dusk (US Center for Disease Control and Prevention [CDC], 2016).

Once infected, a human host can display symptoms between 3-12 days later. The virus can also be transmitted through sexual contact. It is thought that it might also be passed in blood and saliva, though this has not yet been proven.

When a woman is infected in pregnancy, the Zika virus can also cross the placenta and infect the fetus in utero (WHO, 2016). There is no evidence that Zika can be transmitted from household pets or from general contact with others.

What are the symptoms of Zika?

Unlike its more virulent cousin Dengue, Zika virus is comparably mild. Four in five sufferers of Zika have no symptoms, so it is possible to be infected and not know.

Zika maculopapular rash. Photo credit: www.reshareworthy.com

For those who do develop symptoms, Zika typically causes very mild and innocuous flu-like symptoms, joint and generalized aches and pains, low-grade fever and a maculopapular rash that starts at the face and neck and travels down the body (see photo).

Unlike dengue, however, Zika sufferers will experience conjunctivitis: irritation of the conjunctiva causing redness and itching of the eyes.

Possible side effects

Whilst the Zika virus is relatively mild, the possible side effects of infection are serious. There has been a correlation of increase in cases of Guillain-Barre Syndrome following Zika infection (Wilson et al., 2016). This is an acute condition which affects the peripheral nervous system, starting with numbness in the lower extremities ascending up the body over a period of 2-3 weeks. In the most serious of cases (20-30% of cases), it can cause paralysis. Recovery from Guillain-Barre Syndrome is slow and involves extensive therapy.

In March 2016 following a systematic review of the available evidence, the World Health Organisation (2016) declared a global consensus that Zika virus infection in pregnancy is likely to be the cause of increased incidences of microcephaly (small heads) in babies.


Microcephaly (see below figure) is a condition where the baby’s head is much smaller than expected (Frazer and Cooper, 2009). A baby’s head grows because its brain grows, so microcephaly results when the brain stops growing in utero or just after birth.

Microcephaly vs. normal head size. Photo credit: www.srilankanscientist.com

Zika is not the only cause of microcephaly; it can occur as a result of a genetic or chromosomal abnormality. Also, certain infections in pregnancy (e.g., Zika, rubella, cytomegalovirus, and toxoplasmosis), as well as poor lifestyle (severe malnutrition or alcohol use in pregnancy) are known to interfere with brain development and hence increase the risk of microcephaly (NINDS, 2016).

In addition to the physical disfigurement, babies with severe microcephaly may experience seizures, developmental delay, hearing and sight problems and learning difficulties (CDC, 2016).

Detecting microcephaly

Microcephaly can be indicated in the ultrasound scan, but definitive diagnosis is often not possible until after birth. Presence of Zika virus in the amniotic fluid does not always result in microcephaly, as it is usually in the first and second trimesters that the risk is greatest.

Microcephaly in Thailand

There are no official reported statistics for the incidence of microcephaly in Thailand, though Praset Thoncharoen, a Thai virologist, was recently quoted in the press as stating that the incidence was 4.3 per 100,000 births—that’s twice the global average (Al Jazeera, 30 Sept 2016).

Implications for pregnancy?

Contemplating pregnancy: Consider delaying

Current health advice for anyone living within a Zika-affected zone who is contemplating pregnancy is to consider delaying conception to avoid the risk of Zika complications. If you decide to proceed, it is advised that you undergo conception counseling with your doctor and both you and your partner be tested before trying to get pregnant, and you remain vigilant to avoid mosquito bites and be mindful of any symptoms.

If you or your partner are known to have had Zika virus, it is suggested that you delay trying for a baby, in the case of women for at least 8 weeks and for men for at least 6 months, as the virus has been found to survive in semen for up to 6 months (Barzon et al., 2016).

Already pregnant: Avoid mosquito bites

If you are already pregnant, then the current advice from CDC and WHO centers around prevention of infection since there is no vaccine for Zika virus, and re-infection can occur many times. The serious implications for pregnancy (severe microcephaly) are not reversible and not curable, therefore prevention of infection is paramount.

The WHO recommendations for mosquito bite prevention are below.

Already pregnant: Use barrier contraception/abstain

As Zika can be sexually transmitted, and, as previously mentioned, the virus is known to remain present in semen for six months (Barzon et al 2016), it is advised that pregnant women use barrier methods of contraception (such as condoms) or abstain from sexual intercourse for the duration of their pregnancy.

The WHO also recommends, where possible, control of mosquito populations to lessen the risk of exposure to Zika. This may lead to a rise in the use of insecticides to fog areas to kill Aedes mosquitos.

Testing in pregnancy

At present, there are no plans for blanket testing of pregnant women for Zika, though the Thai Ministry for Health is looking into the feasibility of providing free testing for all pregnant women (Reuters, 3 October 2016). The test is relatively inexpensive, though the frequency of testing required could make it untenable. 

If you think you have been exposed to Zika you should contact your OB/GYN for guidance. Close monitoring of pregnant patients with Zika infection involved amniocentesis or CVS (Chorionic Villi Sampling) to check for the presence of Zika virus in the fetus and close monitoring of fetal growth.

Many pregnant women giving birth in the large international hospitals in Bangkok are subjected to serial ultrasound scans and close monitoring throughout pregnancy as standard. Any deviation from what is considered normal growth should be fully investigated.

Relatively speaking, the number of confirmed cases of Zika infection in Thailand is small (just under 400 in a population of 67 million). However, despite the low overall risk, it is still vital to remain vigilant to avoid exposure to the virus and to seek medical attention if you suspect you or your family has been exposed to it. 

If you have any further questions regarding Zika and pregnancy, please contact your OB/GYN. This article is intended for information purposes and should not be taken as a substitute for direct medical advice.




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Disclaimer: This article is intended for information purposes and should not be taken as a substitute for direct medical advice. All statistics quoted were correct at time of going to press.

Cover image by tanakawho via Flickr


About the Author

Originally from Ireland, Emma is a UK-trained midwife who worked in the maternity unit at a busy NHS hospital just outside London. Emma moved to Bangkok with her husband in 2014; they have a 12-year-old son, Toby. Volunteering with BAMBI Bumps and Babies since August 2015, Emma regularly conducts sessions on pregnancy, birth, breastfeeding, and Infant First Aid. In her spare time, she enjoys baking and Muay Thai and is an active member of her son’s parent group at school.

The views expressed in the articles in this magazine are not necessarily those of BAMBI committee members and we assume no responsibility for them or their effects.

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