Where's my brain? What happens to your memory in pregnancy

Are you pregnant and feeling like your brain is on permanent hiatus? You're not alone - one researcher says that the memory of a pregnant woman is like that of a 60-year-old. Dr Melanie Woodfield looks into the research on 'preggy brain' and discovers it's not all in your head.

It's known by many terms, in many countries, and it's the bane of many a mother's existence. Whether you call it "baby brain", "preg head", "mummy brain", "preggy brain", or "nappy brain", losing a few of your marbles during pregnancy seems inevitable. But is this a substantiated fact, or is it another one of the numerous pregnancy old wives' tales? Do we really lose our memory and have trouble concentrating, and, if we do, are there any other abilities that are heightened to make up for it? Stay tuned to find out. That is, if you're able to concentrate for long enough…

Fatigue
Fatigue is worth mentioning first. A pervasive sense of tiredness seems to hit almost from the first day of your missed period. The tiredness is often profound, and can't be shifted by a good night's sleep. The first and third trimesters are reported by many women to be the worst for tiredness, although some mums-to-be suffer all the way through. Second and subsequent pregnancies seem to bring more tiredness with them. Whether it's the energy required for caring for another child, or the lack of a "romantic" sense of being pregnant to help alleviate the fatigue, there's no doubt it's an exhausting business. And with that exhaustion comes the potential for a collection of side-effects, affecting physical and mental ability. Fatigue is likely to exacerbate any pre-existing memory, attention or concentration difficulties, which is worth bearing in mind, when you're wondering if you've lost your mind.

General ability
In 2003, RHM de Groot and colleagues decided to find a group of women in early pregnancy (14 weeks in this case) and match them with a group of non-pregnant women who matched as closely as possible in key areas such as age and educational achievement. De Groot ended up with 71 pregnant women and 57 "control" women. The women were administered a battery of different tests focusing on these areas: Intentional learning (deliberate learning of new material), retrieval from semantic memory (remembering words), and speed of information processing (how rapidly we make sense of information). Interestingly, the researchers found statistically significant differences between the two groups of women in the first two aspects - pregnant women had more difficulty learning new material and with this particular aspect of memory. There was no difference between the groups with information processing speed.

The authors cautioned that the memory differences that they did find were very small, that the study itself was rather small, and that a "longitudinal" design would have been more appropriate to determine clear associations between cognitive performance and pregnancy. But this study was somewhat unique, in that it examined neuropsychological performance in the wider sense. It seems that the majority of studies into the cognitive performance of pregnant women have looked at memory. A substantial number of studies have been carried out, with rather conflicting results. We will look at these in detail in a moment.

Memory
Memory does seem a rather relevant aspect to examine. Many mums-to-be experience a sense of befuddlement that wasn't there before they had children. Have you ever forgotten your best friend's baby's name, your mother-in-law's phone number, or completely blanked as to where you left that all-important packet of wipes? There's no doubt that, anecdotally, our memory is not at its best when we're pregnant or parenting young children. But is this a true change in memory ability, or is it simply a product of being distracted, tired, and stressed? Or, could it be both?

Julie Henry and Peter Rendell, a pair of Australian researchers from the University of New South Wales and the Australian Catholic University in Melbourne, respectively, have attempted to answer this question. They pooled together all of the studies they could find (14 studies over the past 17 years) that had examined pregnant women's memory and had compared this with non-pregnant women's memory. They noted that, interestingly, pregnant women almost always describe themselves as more forgetful than before pregnancy. For this reason, Drs Henry and Rendell were very careful to ensure they only included studies that had formally assessed memory, and not simply asked women to describe their own memory ability.

What they found was very interesting. Pregnant women's memory was definitely worse (in some areas) than non-pregnant women, and forgetfulness continued for several months after the baby was born. The researchers did point out that the differences between the groups were very small. In The Observer, Dr Henry likened the memory of a pregnant woman to that of a non-pregnant 60-year-old. She was also quoted as saying "regular, well-practised memory tasks are unlikely to be affected, such as remembering phone numbers of friends and family members. However, the ability to perform more novel memory tasks, such as having to remember new phone numbers or people's names, or recalling five or six digits for a short period of time, may be affected."

Henry and Rendell weren't able to draw conclusions about why memory was impaired, but highlighted possible influences such as hormonal changes, changes in brain chemistry, mood changes, cultural stereotypes, and lifestyle factors. In The Observer, Dr Henry said, "Our own suspicion is that lifestyle may be a relevant factor to consider; for example, the increased disruption and dislocation of pregnancy, busyness and the lack of routine associated with this period. Sleep deprivation is also going to be a relevant factor post-pregnancy that could affect cognitive performance." If we're tired, we're less likely to fully attend to a task. Our brains then process the information less effectively, and we're therefore less likely to remember it later on.

These results are not always supported, however. In fact, several studies have found that pregnancy has no effect on memory. A well designed study involving 2,500 women who were tested repeatedly over a 10-year period showed that pregnancy had no effect on memory at all. The study was reported in early 2009, and carried out by Professor Helen Christensen and her team at the Australian National University in Canberra. It's worth paying attention to these results, as the longitudinal design and large sample size make for an authoritative study!

Another smaller study was carried out by Dr Ros Crawley, a psychologist from the University of Sunderland, in 2003. Dr Crawley compared 15 pregnant women with 14 matched non-pregnant women on various measures of attention and memory. The women were tested twice during pregnancy, and at six and 12 months after birth. While the pregnant women rated their own memory and attention as worse than normal,  the actual performance of the two groups was the same.

Professor Christensen and Dr Crawley had two possible explanations for this. First, the possibility that pregnant women's memory and attention is impaired, but that the measures used weren't sensitive enough. The second possibility is that mood swings are to blame (aren't they always?), or that the women expected to have "baby brain" during pregnancy, which made them more aware of forgetting things, and, because of this social/cultural expectation that their memory was poor, they attributed this normal forgetfulness to their pregnancy. Interesting!

Even more interesting is that some researchers have asserted that pregnancy actually makes mums smarter! Animal research involving rats, that can be applied to humans (believe it or not), suggests that rat mothers are better at multi-tasking and show less fear than rats without children. Could it be that, because we're so busy, we don't have time to dwell on those things that make us anxious, and we have to be faster and more efficient at what we do? This despite the difficulty we might have in imagining a multi-tasking rat mummy talking on her mobile phone while finding a lost sock and helping her rat son with his homework.

Attention and concentration
Towards the end of my first pregnancy, I found it difficult to concentrate on anything but the impending arrival of my baby. Thankfully, apparently this is fairly common. So common, in fact, that there's even a name for the situation - "primary maternal preoccupation". Donald Winnicott, a paediatrician and child psychoanalyst, first described the condition in 1956. Essentially, the term refers to the emotional and psychological processes that mothers undergo in order to prepare for motherhood. As this is a hypothetical state of mind, it's rather difficult to test empirically, but worthy of note nonetheless.

Interestingly, one researcher has suggested that spending time in nature, or on "natural-type" pursuits can help pregnant women's concentration. This observation is based on one small study, which means we can't draw too many powerful conclusions, but it seems that "spending 120 minutes each week in restorative activities involving nature" can help with concentration. Take a look at Mary Ann Stark's 2003 study for more information if you're interested, preferably while sitting under a tree.

Sense of smell
It's not talked about as often as memory loss, but another brain-related phenomenon that occurs during pregnancy involves our senses of taste and smell. Weirdly, we seem to become super-sensitive to even the slightest whiff , or the most microscopic trace of an element in our food or drink. This can be used to our advantage, as in the case of the team of wine tasters at Tesco supermarkets, who were reported by The Guardian newspaper in 2004. Four of the team of wine tasters became pregnant around the same time, and all noticed that their sense of taste and smell had been enhanced - one of the team commented that "it's as if the volume has been turned up on the flavours". Tesco decided to capitalise on this experience, and ran a campaign calling for pregnant women to join their team of wine tasters! Shocked? Don't worry - the company emphasised that wine tasting involves spitting the wine out, and not swallowing it.

Interestingly, there's actually some research evidence to support the idea that our sense of smell changes during pregnancy. Steven Nordin and his Swedish colleagues carried out a study in 2004 that surveyed approximately 140 women at 13-16 and 31-34 weeks of pregnancy, and 9-12 weeks after baby was born. These results were compared with surveys completed by non-pregnant women. The findings from this study were based on a "self-report" measure; in other words, women reported their own experiences, as opposed to a more "objective" measure of changes in smell.

Despite this, the results were compelling. Abnormal smell and/or taste sensations were reported by 76% of pregnant women! These women mainly related this change to the pregnancy itself. Increased sensitivity to smells was most prominent in early pregnancy, and this was occasionally accompanied by smell distortions and/or "phantom" smells. These differences were less common in later pregnancy, and almost completely absent after baby was born. 26% percent of women also described a change in taste - typically reporting decreased salt sensitivity (needing more salt to actually taste it), and an increased sensitivity to bitter tastes.

So it seems that we become better multi-taskers, more bold, and better at smelling and tasting when we're up the duff. On the flip side, we might (or might not) have more difficulty remembering new information and concentrating well.

Despite the difficulty we've had in finding a single, unanimous, authoritative study, it certainly seems that enough women have anecdotally reported changes in their cognitive functioning to make this area worth studying. Next time a friend or colleague blames a slip-up on "baby brain", have some sympathy - she's not alone.

Dr Melanie Woodfield is a clinical psychologist in Auckland. She can't remember any memory loss during pregnancy, but does recall being able to smell a burger at 100 paces!