Your week 3 guide

The fertilised egg carries a complete set of genetic instructions from the moment sperm and egg combine. Twenty-three chromosomes from each side pair up into forty-six, and that single event settles your baby's sex, eye colour and countless other characteristics long before any of them can be seen. Nothing further needs to be added to that blueprint; the coming months are about reading it out.

Rapid cell division turns one cell into a hollow ball called a blastocyst. The cell divides roughly every twelve to twenty hours while still travelling, so by the time it reaches the uterus it is a cluster of around a hundred cells rather than one. Its overall size has barely changed, because the cells are dividing rather than growing.

The blastocyst has already split into two populations of cells with different futures. The outer layer will become the placenta and membranes, while a small inner cluster will become the embryo itself. It is worth knowing that much of this early activity is building the life-support system rather than the baby, which is why the placenta is so far ahead of everything else.

You will almost certainly feel no different this week. Fertilisation produces no sensation, and the embryo is still microscopic and not yet connected to your blood supply. Feeling nothing at this stage is the ordinary experience, not a sign that something has gone wrong.

Mild bloating, tiredness or light spotting can occur now for entirely ordinary reasons. Progesterone rises after ovulation whether or not conception occurs, which is why this week can feel identical to the run-up to a period. Any bleeding that is heavy, worsening, or comes with significant pain still deserves a call rather than a wait.

A test may just turn positive at the very end of this week, but a negative result still means very little. hCG only starts rising after implantation, and it takes a few days to reach a level a home test can pick up. Testing too early and getting a negative is the most common false alarm in early pregnancy.

If a test is negative but your period has not arrived, wait a few days and test again with first-morning urine. hCG doubles roughly every two to three days in early pregnancy, so a few days can be the difference between a blank window and a clear line. Testing repeatedly on the same day only adds anxiety without adding information.

Work out your estimated due date from the first day of your last period. Having an approximate date makes the rest of pregnancy legible, from when your scans fall to when you might need to talk to work. Hold it loosely, though, because it is a projection and only about one baby in twenty arrives on it.

Keep taking your prenatal vitamin and look at the everyday exposures around you at home and at work. Strong cleaning products, solvents, pesticides and paint stripping are worth handing to someone else or leaving until later, and changing cat litter is the one household job to pass on, because of toxoplasmosis. None of this needs to become a fear of your own house; it is a short list you deal with once. InshaAllah, sharing the heavier household jobs can leave you a little more breathing room.

Folate from food: Folate is vitamin B9, found naturally in many foods. Folic acid is a form used in supplements and fortified foods. Folate contributes to cell division, DNA formation and the early development of your baby's nervous system.

Sources include leafy green vegetables, broccoli, cabbage, beans, lentils, chickpeas, peas, citrus fruits, wholegrains and fortified foods. These foods sit alongside your recommended folic acid supplement and do not replace it, because the amount needed in early pregnancy is difficult to reach from diet alone.