The Science Behind Week 4 of Pregnancy
By week 4, the blastocyst implants in the uterine lining and hCG production begins, which is what a pregnancy test detects. the physiology and evidence, explained without jargon for expectant parents.
The KK Baby editorial team researches, writes and fact-checks every guide on this site. We work from national health guidance, obstetric and paediatric bodies and peer-reviewed research, and we re-check health content on a rolling schedule.
By week 4, the blastocyst implants in the uterine lining and hCG production begins, which is what a pregnancy test detects. the physiology and evidence, explained without jargon for expectant parents.
· 6 min read
Side-opening cribs make night feeds easier while keeping a separate sleep surface. the highest-leverage habits, ranked by how much they help for parents planning purchases.
· 6 min read
Side-opening cribs make night feeds easier while keeping a separate sleep surface. the highest-leverage habits, ranked by how much they help for parents choosing baby gear.
· 6 min read
Soft steamed carrot batons, ripe pear, omelette strips, pasta twists and toast fingers. what to do when it happens in the middle of the night for parents starting solids.
· 5 min read
Impetigo and infected eczema need prompt treatment. what to do when it happens in the middle of the night for parents managing a baby’s health.
· 5 min read
Crying peaks around six weeks and reduces markedly by four months. the highest-leverage habits, ranked by how much they help for new parents.
· 5 min read
Bedtime battles usually mean the wake window is wrong or autonomy needs an outlet. the version nobody explains before you need it for parents of babies and toddlers.
· 5 min read
By week 8, fingers and toes are forming as webbed paddles and the embryo starts making small spontaneous movements. a printable list that covers everything without the padding for expectant parents.
· 5 min read
Red meat, liver, lentils, beans, fortified cereal and dark leafy greens. how to prepare for the stage that follows this one for parents starting solids.
· 5 min read
Hard pellets and pain on passing stool define constipation, not frequency alone. how to prepare for the stage that follows this one for parents managing a baby’s health.
· 5 min read