Content last reviewed August 26, 2026
Every developmental and maternal-health claim in Knitty is drawn from the sources listed below, not invented or adapted from other pregnancy apps or guides. Where reputable sources genuinely disagree — on a size figure, a timing window, or a term like “viable” — we describe the range or say plainly that sources differ, rather than picking one answer and presenting it as settled fact.
ACOG
The American College of Obstetricians and Gynecologists
Clinical definitions (term-pregnancy stages, fetal-growth stages) and patient FAQs. The primary reference this app defers to when other sources disagree.
NHS
The UK's National Health Service
Week-by-week developmental milestones, size comparisons, and common-symptom guidance.
Mayo Clinic
Mayo Clinic
Fetal development figures (size, weight, milestones) and general pregnancy-care guidance.
Cleveland Clinic
Cleveland Clinic
Early first-trimester development, including the embryo-to-fetus transition.
CDC
The U.S. Centers for Disease Control and Prevention
The Hear Her maternal warning-signs list — the basis for this app's red-flag symptom guidance.
MedlinePlus
MedlinePlus, U.S. National Library of Medicine
Fetal development reference material and patient care instructions.
NICHD
The Eunice Kennedy Shriver National Institute of Child Health and Human Development
Term-pregnancy definitions and general developmental reference.
Nemours KidsHealth
Nemours KidsHealth
Week-by-week developmental milestones and common-symptom guidance, cross-checked against NHS.
This content is educational only, written in general terms — it is not medical advice and doesn’t reflect any individual’s situation. Always defer to a qualified healthcare provider for anything specific to your pregnancy.
If something here looks wrong or out of date, tell us at support@knitty.baby.