Benefits, harms, and costs
- 1When fetal microcephaly is suspected, timely referral to a tertiary ultrasound unit should be undertaken for further assessment and to optimize clinical management options (II-2A).
- 2When fetal microcephaly is confirmed by measurement of a head circumference less than or equal to 3 standard deviations below the mean, a thorough and detailed fetal anatomic survey should be undertaken, with focus on cerebral findings and extracerebral signs associated with congenital infection, potential teratogenic exposures, as well as possible chromosomal anomalies or monogenic conditions (II-2A).
- 3When fetal microcephaly is identified, the pregnant woman should be offered a timely consultation with a maternal-fetal medicine specialist and a medical genetics specialist, ideally within a multidisciplinary setting (III-A).
- 4Evaluation of the pregnancy presenting with fetal microcephaly should include:
- aMaternal health assessment and inquiries about maternal conditions associated with poor fetal cerebral growth (for example, phenylketonuria) (II-2A)
- bDetailed review of potential teratogenic and environmental exposures (II-2A)
- cDetailed family history and evaluation of parental head size (III-A)
- dEvaluation of potential infectious causes (II-2A)
- eDiscussion of potential additional investigations such as chromosome or single gene analyses, when clinically indicated (III-B)
- 5Once fetal microcephaly is identified by ultrasound, fetal magnetic resonance imaging, when available and if potential findings are likely to alter pregnancy management, may be considered. Fetal magnetic resonance imaging images should be reviewed by a radiologist with expertise in fetal magnetic resonance imaging (III-A).
- 6In ongoing pregnancies with fetal microcephaly, ultrasound examination should be repeated periodically to assess the evolution of the microcephaly and attempt to detect other anomalies not previously identified, as this may influence the counselling as well as the obstetrical or perinatal management (II-2B).
- 7A comprehensive newborn assessment is essential for diagnosis and counselling on the etiology, prognosis, and recurrence risk for future pregnancies, especially when the etiology has not been clearly identified prenatally (III-A).
- 8In cases of termination of pregnancy, stillbirth, or neonatal death, the most responsible health provider should encourage the performance of a complete autopsy by a perinatal or pediatric pathologist to provide maximum information on the diagnosis and etiology of the microcephaly. When a complete autopsy is declined, the performance of at least a partial or external autopsy (including photographs and postnatal magnetic resonance imaging, when available) should be offered (III-A).
- 9Depending on the underlying etiology or in the absence of an identified underlying diagnosis in a previous affected pregnancy, tertiary care ultrasound referral for assessment of fetal head growth for future pregnancies should be considered (III-A).
Abbreviations:CMV (cytomegalovirus), HC (head circumference), MRI (magnetic resonance imaging), SD (standard deviation)
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- Practice parameter: evaluation of the child with microcephaly (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology and the Practice Committee of the Child Neurology Society.Neurology. 2009; 73: 887-897
- A prospective study of the accuracy of ultrasound in predicting fetal microcephaly.Obstet Gynecol. 1987; 69: 908-910
- Ultrasound criteria for in utero diagnosis of microcephaly.J Clin Ultrasound. 1980; 8: 11-16
- Prenatal screening for microcephaly: an update after three decades.J Perinat Med. 2017; 45: 167-170
- Ultrasound screening for fetal microcephaly following Zika virus exposure.Am J Obstet Gynecol. 2016; 214: B2-B4
- Diagnostic accuracy of ultrasound scanning for prenatal microcephaly in the context of Zika virus infection: a systematic review and meta-analysis.Sci Rep. 2017; 7: 2310
- Prediction of microcephaly at birth using three reference ranges for fetal head circumference: can we improve prenatal diagnosis?.Ultrasound Obstet Gynecol. 2016; 47: 586-592
- The diagnosis of fetal microcephaly.Am J Obstet Gynecol. 1984; 149: 512-517
- Congenital microcephaly in Quebec: baseline prevalence, risk factors and outcomes in a large cohort of neonates.Arch Dis Child Fetal Neonatal Ed. 2018; 103: F167-F172
- Prevalence and clinical attributes of congenital microcephaly - New York, 2013-2015.MMWR Morb Mortal Wkly Rep. 2017; 66: 125-129
- Prevalence of microcephaly in Europe: population based study.BMJ. 2016; 354: i4721
- Selected birth defects data from population-based birth defects surveillance programs in the United States, 2006 to 2010: featuring trisomy conditions.Birth Defects Res A Clin Mol Teratol. 2013; 97: 709-725
- Diagnostic approach to microcephaly in childhood: a two-center study and review of the literature.Dev Med Child Neurol. 2014; 56: 732-741
- Outcomes of fetuses with small head circumference on second-trimester ultrasonography.Prenat Diagn. 2012; 32: 869-874
- Developmental outcome of isolated fetal microcephaly.Ultrasound Obstet Gynecol. 2010; 36: 154-158
- Corrected head circumference centiles as a possible predictor of developmental performance in high-risk neonatal intensive care unit survivors.Dev Med Child Neurol. 2005; 47: 766-770
- Prenatal and postnatal growth and cognitive abilities at 56 months of age: a longitudinal study of infants born at term.Pediatrics. 2008; 121: e1325-e1333
- Health and development at age 19-24 months of 19 children who were born with microcephaly and laboratory evidence of congenital Zika virus infection during the 2015 Zika virus outbreak - Brazil, 2017.MMWR Morb Mortal Wkly Rep. 2017; 66: 1347-1351
- No. 240–cytomegalovirus infection in pregnancy.J Obstet Gynaecol Can. 2018; 40: e134-e141
- A series of 238 cytomegalovirus primary infections during pregnancy: description and outcome.Prenat Diagn. 2013; 33: 751-758
- The prognostic value of ultrasound abnormalities and biological parameters in blood of fetuses infected with cytomegalovirus.BJOG. 2008; 115: 823-829
- Ultrasound prediction of symptomatic congenital cytomegalovirus infection.Am J Obstet Gynecol. 2008; 198: 380.e1-380.e7
- How does imaging of congenital Zika compare with imaging of other TORCH infections?.Radiology. 2017; 285: 744-761
- Phosphoglycerate dehydrogenase (PHGDH) deficiency without epilepsy mimicking primary microcephaly.Am J Med Genet A. 2017; 173A: 1936-1942
- On the phenotypic spectrum of serine biosynthesis defects.J Inherit Metab Dis. 2016; 39: 373-381
- An update on serine deficiency disorders.J Inherit Metab Dis. 2013; 36: 613-619
- Prenatal and early postnatal treatment in 3-phosphoglycerate-dehydrogenase deficiency.Lancet. 2004; 364: 2221-2222
- Congenital microcephaly and seizures due to 3-phosphoglycerate dehydrogenase deficiency: outcome of treatment with aminoacids.J Inherit Metab Dis. 2002; 25: 119-125
- Determination of gestational age by ultrasound.J Obstet Gynaecol Can. 2014; 36: 171-181
- Diagnostic imaging tools to elucidate decreased cephalic biometry and fetal microcephaly: a systematic analysis of the central nervous system.Ultrasound Obstet Gynecol. 2016; 48: 16-25
- No. 365-fetal and perinatal autopsy in prenatally diagnosed fetal abnormalities with normal chromosome analysis.J Obstet Gynaecol Can. 2018; 40 (.e5): 1358-1366
This document reflects emerging clinical and scientific advances on the date issued and is subject to change. The information should not be construed as dictating an exclusive course of treatment or procedure to be followed. Local institutions can dictate amendments to these opinions. They should be well documented if modified at the local level. None of these contents may be reproduced in any form without prior written permission of the publisher.
All people have the right and responsibility to make informed decisions about their care in partnership with their health care providers. In order to facilitate informed choice, patients should be provided with information and support that is evidence-based, culturally appropriate and tailored to their needs.
This guideline was written using language that places women at the centre of care. That said, the SOGC is committed to respecting the rights of all people – including transgender, gender non-binary, and intersex people – for whom the guideline may apply. We encourage health care providers to engage in respectful conversation with patients regarding their gender identity as a critical part of providing safe and appropriate care. The values, beliefs and individual needs of each patient and their family should be sought and the final decision about the care and treatment options chosen by the patient should be respected.