Forgetting where you left your keys, losing your train of thought, struggling to focus: many pregnant women describe a fog they call “pregnancy brain” or “mommy brain.” For years it was brushed off as a joke. Research led by neuroscientist Elseline Hoekzema at Leiden University in the Netherlands suggests the brain really does change during pregnancy, and that the changes may serve an important purpose.
Building on earlier findings
Pregnancy floods the body with hormones on a scale not seen at any other time in life. In animals, those hormones are known to reshape the brain and drive maternal behavior. In an earlier study, Hoekzema’s team found that women lost gray matter volume in specific brain regions during their first pregnancy, and that many of those changes lasted for years. The question was how and why.
Those earlier changes were concentrated in brain regions involved in social understanding, the skills we use to read other people’s needs and intentions. That fits the idea that the changes help mothers tune in to their babies.
How the new study worked
For a study published in Nature Communications in 2022, the team scanned the brains of women before pregnancy, during pregnancy, after birth and about a year later. They compared the results with women who did not become pregnant over the same period. The pregnant group also provided regular urine samples so researchers could track hormone levels, and answered questionnaires about sleep, mood and “nesting” behavior.
What they found
- Brain networks changed during pregnancy. The biggest changes were in the default mode network, a set of brain regions that is active when we reflect, daydream and think about ourselves and others.
- Hormones were linked to the changes. The brain changes tracked with rising levels of pregnancy hormones.
- The changes may support bonding. The researchers found links between the brain changes and behaviors such as nesting during pregnancy and attachment to the baby afterward.
The researchers suggest pregnancy may give the brain a kind of blueprint that supports the developing relationship between mother and baby, which is then strengthened through day-to-day interaction. In that light, some of the forgetfulness of pregnancy may be a side effect of the brain reorganizing its priorities.
The study was small, and the researchers note that more research with larger groups is needed to understand exactly what changes and why.
What this means for you
If you’re pregnant or recently gave birth and feel foggy, you’re not imagining it, and you’re not alone. A few strategies can help:
- Lean on reminders. Lists, phone alerts and a shared calendar take pressure off your memory.
- Protect your sleep where you can. Poor sleep makes concentration harder. Rest when you can and accept help.
- Eat regularly and stay hydrated. Steady energy supports focus.
- Go easy on yourself. These changes are a normal part of pregnancy and are not a sign that something is wrong.
- Know when to get help. Feeling persistently sad, anxious, hopeless or unable to cope is different from ordinary fog. Talk with your doctor or midwife, as these can be signs of perinatal depression or anxiety, which are common and treatable.
The bottom line
“Pregnancy brain” reflects real changes in the brain, driven by the surge of pregnancy hormones. Rather than a flaw, those changes may help prepare mothers to bond with and care for their babies.
This article is for general information and isn’t medical advice. Talk with your healthcare provider about your individual needs.
