Some people carry a chunk of Neanderthal DNA that appears to reduce the chance of miscarriage and increase fertility
Source:
https://www.newscientist.com/article/2244492-neanderthal-dna-linked-to-higher-fertility-in-modern-humans/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home