Week 7 of Pregnancy: A Blueberry, and the Week the Brain Grows Fastest

Where week 6 was about morning sickness classically starting (or, for some of us, not), week 7 is where the pace of development inside really picks up — even though from the outside, this is often just another week of adjusting how you live.

What’s actually happening in your body

The embryo is now about 10mm long, roughly the size of a blueberry, and its brain is developing at a genuinely fast clip — generating around 100 new brain cells every minute, according to NHS guidance on week 7 of pregnancy. That rapid brain growth is also why the forehead looks disproportionately large at this stage. Small dimples are forming where the nose and ears will eventually be, and the limb buds from last week are starting to develop cartilage that will later become bone.

What I actually felt

My energy was still generally good this week, but I noticed I was getting tired faster than I normally would — not exhausted, just running out of steam a bit sooner in the day. That was enough for me to start being more deliberate about it: I cut back on working late, and treated a good night’s sleep as non-negotiable rather than optional. Exercise didn’t stop, but it did change shape — I kept it going, just at a gentler pace than before, and a daily walk became the one constant I didn’t drop.

Staying active this week

If you’re wondering whether you should keep exercising at all, the general guidance is yes — you generally don’t need to stop, just adjust. A simple, reliable check is whether you can still hold a conversation while you’re active; if you’re too breathless to talk, that’s the signal to ease off, per the NHS. Walking is one of the easiest ways to stay consistent — about 30 minutes a day is a reasonable target, but any amount is better than none, and it’s fine to slow down further as the pregnancy progresses or if your maternity team advises it.

Nutrition focus this week

Nothing new to add here specifically — the same fundamentals from previous weeks still apply. If you haven’t already, our guide to foods and drinks to limit or avoid during pregnancy is worth a read, alongside keeping up with a prenatal vitamin as covered in when to start prenatal vitamins.

What to discuss with your doctor or midwife

If you’re unsure what level of activity is appropriate for you specifically — especially if you have a pre-existing condition, a history of pregnancy complications, or were not very active before pregnancy — this is a good week to ask. Fatigue patterns are also worth mentioning at your first appointment, even if they feel minor now.

Frequently asked questions

Is it normal to feel more tired than usual but not exhausted?

Yes — fatigue in early pregnancy exists on a spectrum. Feeling like you run out of energy a bit sooner than normal, without full exhaustion, is a common middle ground.

Do I need to stop exercising once I’m pregnant?

No, in most uncomplicated pregnancies you can keep exercising — the advice is to adjust intensity, not stop altogether. The conversation test (can you talk while active?) is a simple way to self-check.

Is walking enough exercise during pregnancy?

For many women, yes. Around 30 minutes a day is a reasonable target, but any amount of walking is beneficial, and it’s a low-risk way to stay active throughout pregnancy.

Why is the embryo’s forehead so large at week 7?

Because brain growth is happening so quickly at this stage that the head, and particularly the forehead, appears disproportionately large compared to the rest of the body. This evens out over the following weeks.

Should I mention fatigue to my doctor if it’s mild?

It’s worth mentioning even if mild — it helps your provider understand your baseline, which matters if fatigue becomes more pronounced later.

References

1. NHS — Your Pregnancy and Baby Guide, Week 7. nhs.uk
2. NHS — Exercise in Pregnancy. nhs.uk