Changes in fetal motility as a result of congenital disorders: an overview

After 35 years of real-time two-dimensional sonography, can we now identify changes in fetal motility indicative of malfunction of the central nervous system in high-risk pregnancies? A literature search on motor assessment procedures (movements specified for body part (SMP), quantity, quality and behavioral state), and motor milestones obtained per fetus (with various congenital disorders) yielded 48 articles describing motility of 104 fetuses. In 67%, SMPs (especially isolated arm or leg movements, breathing and general movements) were assessed. Quantitative aspects were examined in 76%, qualitative aspects in 62% and behavioral states in two fetuses. Abnormal motility can be divided into two main subcategories: hypo- and hyperkinetic, demonstrating decreased variation in qualitative performance (reduced or increased, respectively, amplitude, speed and number of participating body parts, abnormal quantity (reduced or increased, respectively) and reduced differentiation into SMPs. Posture was affected in 40/60 hypokinetic and 4/44 hyperkinetic moving fetuses. The majority of the disorders resulted in an adverse outcome. Fourteen percent survived with a handicap, depending on the underlying disorder. The 16 disorders with hypokinetic motility had mainly an autosomal recessive etiology with no possibility of invasive prenatal diagnosis or conclusive sonographic structural anomalies, in contrast to the 17 disorders with hyperkinetic motility. Within the limitations of the studies, a deeper understanding of affected milestones in motor development can be obtained. Broadening motor assessment procedures from quantitative only to include qualitative aspects, differentiation of SMPs and behavioral states and emphasizing onset and continuity of motility before and after birth will enhance the reliability and predictive value of motility as a parameter in the assessment of fetal condition.