Microcephaly is a condition where a baby is born with a small head or the head stops growing after birth. Microcephaly is neonatal malformation defined as a head size much smaller compared with other babies of the same age and sex. Microcephaly can occur as an isolated condition, or it can occur in combination with other major birth defects.

According to World Health Organization (WHO), microcephaly is a rare condition. One baby in several thousand is born with microcephaly.

Brazil has reported an unusual, sudden increase in babies born with microcephaly since May 2015. Brazilian Live Birth Information System (SINASC) reported the prevalence of microcephaly in Brazilian newborns as 5.5 cases/100,000 live births and 5.7 cases /100,000 live births in 2000 and 2010 respectively. Over the last three months of 2015, it went up to 99.7 per 100.000 live birthsa.

Recently a base line estimate of birth prevalence of microcephaly affected births (total number of babies including both live born and stillborn with microcephaly per 10 000 births) in India was determined after a systematic review and meta-analysis of several studies. The pooled birth prevalence of microcephaly was shown as 2.30 per 10 000 births among 97155 birthsb.

Babies born with micocephaly often have smaller brains which have not developed properly. Other symptoms like convulsions, physical and learning disabilities start to appear as child grows older.

There are no specific tests to determine microcephaly during fetal life, but ultrasound scans in the third trimester of pregnancy can be used to identify the problem. The most reliable method to diagnose the microcephaly in new born is to measure head circumference 24 hours after birth, compare the value with WHO growth standards and continue to monitor the rate of head growth in early infancy.






a. Soares de Araújo JS, et al. Microcephaly in northeast Brazil: a review of 16 208 births between 2012 and 2015 [Submitted]. Bull World Health Organ E-pub: 4 Feb 2016. doi: dx.doi.org/10.2471/BLT

b. Bhide P, Kar A. Birth prevalence of microcephaly in India. [Submitted]. Bull World Health Organ E-pub: 23 Feb 2016. doi: dx.doi.org/10.2471/BLT.

Babies with microcephaly can have different types of symptoms depending upon the severity of microcephaly. Some children with microcephaly will develop entirely normally. Many babies born with microcephaly may show no other symptoms at birth but go on to develop:

  • Epilepsy (Seizures)
  • Delay with developmental milestones like head holding, sitting, standing, walking, or others. 
  • Feeding problems- difficulty in swallowing
  • Problems with speech
  • Learning disabilities (decreased ability to learn and function in daily life)
  • Cerebral palsy (problems with movement and balance)
  •  Hearing loss
  • Vision problems




There are various factors which cause microcephaly in newborns, but often cause remains unknown. The most common causes include following:

  • Genetic abnormalities like Down syndrome,
  • Infections during pregnancy such as toxoplasmosis (caused by a parasite found in undercooked meat), rubella, herpes, syphilis, cytomegalovirus and HIV,
  • Maternal exposure to toxic substances like arsenic and mercury, alcohol, radiation and smoking,
  • Severe malnutrition during fetal life,
  • Interruption of the blood supply to the babies brain (perinatal asphyxia),
  • There is surge in microcephaly in babies born to mothers suffered from zika virus infection during pregnancy; researchers are studying the potential link between the two.  



During the pregnancy:

According to WHO early diagnosis of microcephaly can be done by fetal ultrasound. Ultrasounds should be done at the end of the second trimester, around 28 weeks, or in the third trimester of pregnancy.

In fetuses with head circumference two standard deviations below the mean for gestational age, microcephaly should be suspected.

After child birth:

Head circumference of newborn babies should be measured when newborn baby is at least 24 hours old and compared with WHO growth standards in relation to the gestational age, sex, weight and length of the baby.

The measurement value for microcephaly is usually less than two standard deviations (2SDs) below the average. Severe microcephaly is defined as a head circumference less than three standard deviations (3SDs) below the average for babies of the same age and sex. (This means the baby’s head is extremely small compared to babies of the same age and sex.)

Suspected cases should be reviewed by a pediatrician, brain imaging scans such as computed tomography scan (CT scan), Magnetic resonance imaging (MRI) can be done.  Their head circumference should be measured at monthly intervals in early infancy and compared with growth standards.

Doctors should also test for known causes of microcephaly.




  •  There is no standard treatment for microcephaly. Sometimes medications are needed to treat seizures or other symptoms.
  •  A team of persons of different discipline may help in assessment and care of babies and children with microcephaly.
  •  Family counseling and psychological support for parents should be integral part of the case management.



Complications of microcephaly are secondary conditions or disorders that are caused by microcephaly. Many of the problems associated with microcephaly are developmental delays, problems with vision, hearing, or speech; and epilepsy, trouble moving their arms and legs and problems with feeding because of difficulties sucking and swallowing. A smaller head at birth is also associated with mental retardation.




There are no specific preventive measures; however few known factors causing microcephaly during fetal life may be prevented as-

Before conception-

  • If Rubella Immunization (in the form of measles mumps rubella (MMR) vaccine) is not given during childhood, it should be given to female child and women of childbearing age (prior to conception).
  • Early diagnosis and management of certain infections (rubella, syphilis, toxoplasmosis, cytomegalovirus, herpes) in women who are planning to become pregnant.
  • Advise for avoidance of exposure to toxic substances such as smoking, alcohol.
  • Genetic counseling if there is history of microcephaly in previous pregnancy.
  • Personal protective measures to protect themselves from bites of mosquito that transmit Zika virus.
  • For additional information to women in context of microcephaly and zika virus disease, click here www.who.int

During pregnancy-

  • Mothers should get proper antenatal care during pregnancy including advice on nutrition, screening and management of certain infections, periodic assessment of foetal growth.
  • Women who are pregnant or planning to become pregnant should take extra care to protect themselves from the bites of the mosquitoes by
    • using insect repellent: repellents may be applied to exposed skin or to clothing, and should contain DEET;
    •  wearing clothes (preferably light-coloured) that cover as much of the body as possible (e.g. long sleeves, long trousers or skirts);
    • sleeping under mosquito nets, even when sleeping during the daytime;
    • use of mosquito mesh/nets/screens on windows and doors;
    • use of the above personal protection measures by individuals infected with Zika, dengue, and or chikungunya virus should be encouraged to avoid spread of infection to uninfected individuals (at least during the first week of onset of symptoms);
    • to prevent potential sexual transmission of Zika virus, sexual partners of pregnant women, living in or returning from areas of ongoing Zika virus transmission, should use safer sexual practices (including correct and consistent condom use) or abstain from sexual activity for the duration of the pregnancy;
    • eliminating potential mosquito breeding sites, by emptying, cleaning or covering containers that can hold even small amounts of water, such as buckets, flower pots and tyres.
  •  WHO has released a Decision-chart for the care of pregnant women living in areas with ongoing Zika virus transmission on 2nd March 2016a.

After birth-

  • Early interventions after child birth to promote physical and learning abilities in child.
  • Psychological support for pregnant women and for families with microcephalyb.


a. Pregnancy management in the context of Zika virus- apps.who.int/iris/bitstream/


  • PUBLISHED DATE : Mar 08, 2016
  • PUBLISHED BY : Zahid
  • CREATED / VALIDATED BY : Dr. Aruna Rastogi
  • LAST UPDATED ON : Mar 08, 2016


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