Background

Cartilage-hair hypoplasia (CHH), an autosomal recessive skeletal dysplasia due to RMRP mutations, is characterized by short stature, immunodeficiency, anemia, and increased malignancies. Growth failure has its onset prenatally. Birth and neonatal care in pregnancies with fetal skeletal dysplasia have been studied in some other skeletal dysplasias but there have been no previous studies on these aspects in CHH. In this retrospective cohort study, we reviewed patient records for 35 Finnish children with CHH born in 2000–2023 to evaluate the course and management of pregnancies and deliveries and the prenatal and neonatal findings.

Results

Abnormal growth was observed in prenatal ultrasound in 26/30 (87%) children. Shortness was reported especially in the humeri and femora, but the ultrasound findings also included other abnormalities such as a small rib cage. Abnormal ultrasonographic findings mostly visualized during the second trimester. A prenatal genetic diagnosis was made in 6/34 (18%) cases. The median age at time of postnatal genetic diagnosis was 1 month. The Finnish founder mutation was observed in 94% of all cases. Most children (27/33; 82%) were born full-term but 6 children (18%) were born preterm (at 30 + 4–36+4 weeks). Less than half (11/24; 46%) were born by vaginal delivery and the others by elective (5/24; 21%), urgent (4/24; 17%), or emergency Csection (4/24; 17%). Breech position and other malpresentations were more common (30%) than in the general population (3–4%) and accounted for 10/18 (56%) of the Csection indications. The average 1 min Apgar score was 7.4. The median birth length for full-term neonates was 44.5 cm (40.0–50.0 cm) for boys (n = 10) and 44.0 cm (37.0- 48.0 cm) for girls (n = 16). The median birth length Z-score, adjusted for gestational age, for all was −3.9 (−7.5- −1.0) and below −2.0 in 84%. In 7/19 (37%) cases respiratory support was needed postnatally.

Conclusion

In conclusion, in most CHH pregnancies, growth failure was detected prenatally, the pregnancies were carried to full-term but less than half were born by normal vaginal delivery. At birth 16% had normal length. Respiratory challenges accounted for the majority of the neonatal complications.