I’m now 31 weeks pregnant. The weeks are flying by, and for the most part, I’m relishing all the physical changes in my body and the preparations for this baby. We waited a long time for this pregnancy, and it will probably be my last. I curl around my belly at night and think about the baby growing inside me. I wonder about the person that he or she will become and how our little family will adapt to welcome a second child. (We’ve chosen not to learn the sex of this baby until its birth.)
When I was pregnant with Cee and about to become a mom for the first time, I thought a lot about what kind of mother I would be and how this big life transition might alter my identity, my career path, my marriage, and my daily life. The baby-to-be was kind of a vague amalgamation of all the babies I’d known.
This time around, having been around many more babies, I recognize the individuals that babies are from the first days of life – and even in utero – and I spend a lot more time wondering about this baby’s temperament and personality. Introverted and contemplative, like Cee? Or totally different?
Filling me with wonder, this baby moves around in utero a lot, and this feels very different from my experience carrying Cee. I didn’t feel movement from Cee until around 23 weeks, but I began to feel this baby move at 16 weeks. And this baby continues to be very active, more than I remember with Cee, especially making big, dramatic movements in the evening hours but also having significant activity bouts throughout the day (and sometimes in the middle of the night, of course).
Because we don’t know the sex of this baby, I’m often asked if I have any predictions on that front. How would I know, I think? I don’t feel like I have any kind of gut instinct for this kind of thing, and I don’t buy into any of the old wives tails. But if I’m pushed to make a guess, I guess that this baby is a boy. And when I ask myself why that is, it comes down to this observation about more fetal movements. This baby feels different from Cee, and my brain makes a jump to sex as a possible explanation. And then I stop, remind myself that I’m perpetuating a total gender stereotype, and feel embarrassed.
One day, I repeated all of this to a friend as we walked together (complete with an apology for the gender stereotype), with Cee riding her bike within hearing distance. A couple of weeks later, my mom was talking to Cee on the phone and asked her if she thought the baby would be a boy or a girl. Cee answered in what seemed like a verbatim copy of my own explanation: “Well, Mom thinks that it’s a boy, because the baby moves around a lot inside of her, and I didn’t move very much.” Yikes. From now on, I’m keeping my mouth shut. And for the record, Cee is really hoping for a little sister.
All of this left me wondering if fetal movements can actually predict anything about the baby, whether sex or temperament, in postnatal life. I happened to be corresponding with Jena Pincott, author of Do Chocolate Lovers Have Sweeter Babies?, a few weeks ago, and I asked her if she knew of any research on this. She wrote back, “As for ‘in utero’ forecasts, my prediction is that your 2015 is going to be very, very busy!” and sent me a few research articles. I dug around and found quite a few more studies of this question. Finally, I could stop speculating and start talking science! Here’s what I found:
How is this question studied?
Most studies use ultrasound or a Doppler transducer placed on the mother’s belly to measure fetal movements. Most are conducted over a period of about an hour, during which the moms are asked to rest, and the best studies take several of these measurements over the course of the pregnancy. Studies of postnatal temperament then use standardized behavioral observations or questionnaires to describe aspects of the baby’s behavior.
Is it true that some fetuses are more active than others?
I wondered if my perception that I was carrying a more active fetus is this pregnancy was really true or if it was influenced by other factors? Women in their first pregnancy usually notice fetal movements a few weeks later than those in subsequent pregnancies, but it isn’t clear if number of pregnancies affects detection of fetal movements later in gestation.4,5 Other factors, like position of the placenta and maternal body weight, may play a role.6,5 Although these may add variation to perceptions of fetal movement, studies using objective measures of fetal movements (like ultrasound or Doppler transducers) do consistently find that some fetuses are more active than others. That is, when researchers measure fetal activity at several time points during pregnancy, they find that fetuses that are very active at one time point continue to be very active at later time points.3,7–9 However, I recognize that I’ve personally only felt fetal movements in two pregnancies, and my perception of these movements is probably not entirely objective.
Can fetal activity help us to predict a baby’s sex?
Most studies have found that fetal movements aren’t a reliable predictor of infant sex. For example, two longitudinal studies (measuring fetal activity at several time points during pregnancy), one conducted in both Maryland and Peru and the other from the Netherlands, found no difference in fetal activity patterns between males and females.1,2 As I’d suspected, basing my prediction about my baby’s sex on fetal activity was not evidence-based. It is an understandable mistake, however, because studies have found that, on average, boys are more active than girls in toddlerhood. For example, this study found no difference in activity level between male and female fetuses or as newborns but did find that boys were more active at 1 year of age and tended to be more active at 2 years.3 However, this difference doesn’t seem to trace back to fetal life and may be shaped at least in part by cultural expectations.
Can fetal activity predict a baby’s temperament?
Yes! All of those kicks at my uterus may really have a story to tell about the baby inside of me. A link between fetal activity and postnatal temperament has been observed in multiple studies. Here are a few of the most interesting ones:
- More fetal movements might mean that a baby will cry more. A U.K. study asked pregnant moms to keep 1-hour diaries of fetal movements, classifying each one as weak or strong, in the morning and evening for 3 days at 37 weeks of pregnancy. The moms then completed 24-hour diaries of their babies’ behavior at 1, 6, and 12 weeks postpartum. Strong fetal movements didn’t correlate to later baby behavior, but the number of weak movements did. Fetuses that had more of those weak movements in pregnancy (versus those that had fewer weak movements) ended up fussing and crying more in infancy. On the bright side, fetal movements weren’t correlated to sleeping patterns or feeding behavior.10
- More fetal movements might indicate that a baby is more likely to be more active, unadaptable, and unpredictable. Dr. Janet DiPietro of Johns Hopkins has been studying fetal development for more than 20 years, including several studies of this question of what fetal activity can tell us about our children before their birth. One of the first, published in 1996, found that more active fetuses became babies that were “more difficult, unpredictable, unadaptable, and active,” based on maternal questionnaires at 3 and 6 months of age.
- Babies that move more in pregnancy might be less easily frustrated at 1 year and more independent at 2 years. Another study from Janet DiPietro’s lab included behavioral assessments at 1 and 2 years of age. In one test, the 1-year-old babies watched as a fun-looking toy was placed behind a Plexiglass barrier, out of their reach, and the researchers noted how distressed they were by this set-up (banging on the glass, etc. vs. moving on to something else). In another, the babies were simply strapped into a car seat, a familiar scenario that most of us know can produce frustration in a baby. At age 2, the children were observed playing in their homes while the mothers were instructed to sit close by but to act too busy to interact with their toddlers. There was a correlation between having more fetal activity and being less upset about the 1-year-old tests and playing more independently of mom at age 2. There was also an interesting association with sex in this study. At age 1, boys who were more active in utero were also more active toddlers; however, girls who were more active in utero were the opposite – less active as toddlers.
I think this research is really interesting, but I also am careful to not try to apply it too literally to this child that I haven’t yet had a chance to meet. These studies are specifically trying to separate out fetal movements from many other sources of variation. They look at many babies and use mathematical models to identify patterns in the group, but they really can’t tell us anything about our own particular babies. And I want to be careful not to project my expectations about temperament on my baby or for this to affect how I treat him or her. I’ll do my best to let my baby tell me who he or she is. But in the meantime, it is fun to feel those kicks and wonder about this child. And it doesn’t hurt to be mentally prepared for a baby that might cry a little more than average.
While perusing the research on fetal movements, I also learned a few other fun facts:
- It’s normal to feel stronger fetal movements in the evening hours. In one study, moms reported feeling an average of 4 strong movements per hour in the morning and 12 per hour in the evening.10
- Fetuses that were observed to be sucking their right thumb during ultrasounds were more likely to be right-handed at 10-12 years of age.11
- Maternal cortisol levels during pregnancy were associated with more fetal movements and greater amplitude of movements during the third trimester.12 (But don’t stress about this! I’m not. See above for my cautions about applying this research directly to our own pregnancies.)
- When pregnant moms participated in a guided imagery relaxation exercise, which resulted in physiological signs of relaxation in the moms (lower heart rate, respiration rate, and skin conductance), fetal movements also decreased.13
Did you notice any correlations between fetal activity and your children’s temperament? We’ve talked about the data, and anecdotes are welcome!
- Hijazi, Z. R. & East, C. E. Factors affecting maternal perception of fetal movement. Obstet. Gynecol. Surv. 64, 489–497; quiz 499 (2009).
- Gillieson, M., Dunlap, H., Nair, R. & Pilon, M. Placental site, parity, and date of quickening. Obstet. Gynecol. 64, 44–45 (1984).
- Tuffnell, D. J., Cartmill, R. S. & Lilford, R. J. Fetal movements; factors affecting their perception. Eur. J. Obstet. Gynecol. Reprod. Biol. 39, 165–167 (1991).
- DiPietro, J. A. et al. What does fetal movement predict about behavior during the first two years of life? Dev. Psychobiol. 40, 358–371 (2002).
- DiPietro, J. A., Hodgson, D. M., Costigan, K. A., Hilton, S. C. & Johnson, T. R. Fetal neurobehavioral development. Child Dev. 67, 2553–2567 (1996).
- Groome, L. J. et al. Spontaneous motor activity in the perinatal infant before and after birth: stability in individual differences. Dev. Psychobiol. 35, 15–24 (1999).
- Eaton, W. O. & Saudino, K. J. Prenatal activity level as a temperament dimension? Individual differences and developmental functions in fetal movement. Infant Behav. Dev. 15, 57–70 (1992).
- DiPietro, J. A. et al. Fetal neurobehavioral development: a tale of two cities. Dev. Psychol. 40, 445–456 (2004).
- Robles de Medina, P. G., Visser, G. H. A., Huizink, A. C., Buitelaar, J. K. & Mulder, E. J. H. Fetal behaviour does not differ between boys and girls. Early Hum. Dev. 73, 17–26 (2003).
- St James-Roberts, I. & Menon-Johansson, P. Predicting infant crying from fetal movement data: an exploratory study. Early Hum. Dev. 54, 55–62 (1999).
- Hepper, P. G., Wells, D. L. & Lynch, C. Prenatal thumb sucking is related to postnatal handedness. Neuropsychologia 43, 313–315 (2005).
- DiPietro, J. A., Kivlighan, K. T., Costigan, K. A. & Laudenslager, M. L. Fetal motor activity and maternal cortisol. Dev. Psychobiol. 51, 505–512 (2009).
- DiPietro, J. A., Costigan, K. A., Nelson, P., Gurewitsch, E. D. & Laudenslager, M. L. Fetal responses to induced maternal relaxation during pregnancy. Biol. Psychol. 77, 11–19 (2008).