Dr. Zarrillo then illustrated the growth parameter curves for fetuses of each group. In Group 1, the fetuses “presented similar to the controls” when it came to head circumference, femur growth, and abdominal circumferences. Group 2 showed similar results, to which Dr. Zarrillo noted, “So far, so good.” When it came to Group 2, Dr. Zarrillo pointed out, “This is when we are starting to see some lagging of the head circumference lines and you can actually see that they are somewhat different, but see these fetuses fall somewhere between within the normal range.” Then she showed the graph depicting Group 4: “This is the most concerning for us,” Dr. Zarrillo stressed. “You can see the head circumference growth curve is almost flat; this was statistically significant for two different types of tests.” Femur length and abdominal circumferences were mostly similar.
Dr. Zarrillo went on to explain her team’s findings. First, “fetuses with normal brain imaging whose mothers were affected with Zika infection during pregnancy have smaller head circumferences than controls (P = .0000154). Fetuses whose mothers are affected by Zika during pregnancy prior to 26 weeks of gestation that show no evidence of brain damage on sonography appeared to have a normal growth pattern throughout the rest of the pregnancy.” However, infections that occurred after 26 weeks of gestation “produced a tendency towards smaller head size (p = 0.0175) while other biometric parameters grew within the expected range. These findings require close attention and follow-up since they may be a marker for future developmental anomalies that cannot be prenatally detected.” Lastly, the finding of “postnatal microcephaly, may be the result of such infections occurring late in pregnancy.”
Dr. Zarrillo concluded, “Zika infection during pregnancy can affect brain growth, as measured by the head circumference, even in the presence of normal sonographic imaging. This effect over the growth of the brain is not manifested in other biometric measures such as the femur or abdomen. The significance of such growth patterns on the infant’s future neurologic development is uncertain but definitively worrisome.”
First International Conference on Zika Virus
Session 6: Pregnancy and the Fetus
Head Growth Patterns Among Structurally Normal Fetuses with Symptomatic Zika Viral Infection During Pregnancy in Puerto Rico
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