All posts by Amy Kiefer

As a former research scientist and proud mama of three little munchkins, I love digging into the research on all things baby-related and sharing it with my readers.

Introducing Solids and Baby Sleep: Yep, Early Solids Improve Baby Sleep After All

Don’t give your baby solids until 6 months of age. This is the unambiguous advice of the world’s most highly regard medical organizations, including the American Academy of Pediatrics, the UK’s National Health Service, and the World Health Organization.

Ignore the “mistaken” belief that introducing solids earlier will help your baby sleep better. Early solids could have the opposite effect, worsening your baby’s sleep, according to popular parenting sites like Kelly Mom and the Baby Sleep Site.

Or so we have been told.

It turns out that the claim that solids don’t help baby sleep was based upon the shoddiest of studies–small, non-randomized, poorly controlled–like this one, which simply looked at whether babies were eating solids and how well they slept.

(To be clear–I am not trying to knock this research as research. Small exploratory studies can be very useful for hypothesis generation and deciding on which large studies to run, but the stuff of sound public health pronouncements they are not.)

Now, we finally have much better data, from a randomized trial of over a thousand babies. And surprise, surprise, your mum (or in my case, my mother in law) was right all along: Introducing solids early, at around 3 to 4 months, does improve babies’ sleep. Not just then, but for their entire first year.

The Details

The new study is a secondary analysis of the UK-based Enquiring About Tolerance (EAT) randomized clinical trial, a trial whose main goal was to assess whether early solids lowered the risk of food allergy.

In the trial, researchers randomly assigned 1,303 exclusively breastfed infants to either begin solids at three months (the experimental group) or at around 6 months of age (the control group).

Parents in the experimental group began feeding their babies solids at around 3 months of age, with specific instructions to expose them to six common food allergens (eggs, peanuts, white fish, cow’s milk, wheat, and sesame seeds).

The randomization was highly successful. Nearly all babies in the early introduction group began taking in solids by 4 months of age, whereas almost none of the control babies started solids until after 5 months of age. Notably, nearly all these babies continued to be breastfed, almost none received formula.

Although the EAT trial’s original purpose was to determine if early solids would help prevent food allergies, the study also carefully assessed the babies sleep. Each month, parents reported how long their babies slept at night, how often they awoke at night, and if they felt their babies had mild or severe sleep problems. They also described where their baby slept and how they put their babies to sleep.

Thus, this study represents the largest, carefully constructed randomized trial of how solids affect infant sleep ever performed.

So what did they find?

Babies who received solids early, starting around 3 to 4 months, slept better than controls. They slept a tiny bit longer each night during their first year of life (an average of 6-7 minutes overall, with the biggest difference–17 minutes longer each night–seen at 6 months of age). They were also about 10% less likely to wake up at night. So good, but not really much to write home about.

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Where early solids packed the biggest punch, however, was in preventing sleep problems. While only a small percentage of babies had sleep problems (fewer than 5% overall), control babies were much more likely to be problematic sleepers.

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As shown in the graph below, severe sleep peaked at around 9 months, and then dropped off sharply at a year (good news for many a bleary-eyed sleep beleaguered parent).

Most strikingly, parents of early introduction babies were far less likely to say their babies had mild or severe sleep problems throughout their first year of life–long after the controls were also taking in solids. It appears that early solids helped babies consolidate their nighttime sleep earlier, and this benefit persists throughout infancy.

This latter point was surprising to me, but appears well supported. In fact, the more solids experimental babies ate earlier, the better they slept. (This was a follow-on analysis, and not randomized, but it does lend further support to their main findings.)

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The Bottom Line

So, does this study mean we should all give our babies solids early to help them–and us, let’s not forget us!–sleep better?

By itself, probably not. The effects on sleep are pretty small, overall, (6-7 minutes extra sleep a night; about one less night awakening a week). And before we run completely in the opposite direction and overinterpret these findings, I would really love to see at least one other randomized trial examine the same question.

And we need to note that the babies who slept best in this study (as we already know) were not co-sleeping, slept in their own rooms, and went to sleep by themselves, without parental assistance. These practices had a much bigger impact than solids on baby sleep and remain the foundation for helping your baby sleep well.

That said, let’s step back a second and consider the larger context. Many studies now suggest early solids lower the risk of allergies. This is why many medical organizations that focus specifically on allergies recommend starting solids earlier (4-6 months) than their umbrella counterparts (6 months)–creating schizophrenic, headache-inducing advice for well-meaning parents.

For me personally, speaking as a parent, I would look at these findings and choose to start giving my baby solids at around 4 months of age.

(Introducing peanuts early lowers the risk of peanut allergies. Although the EAT trial did not actually show significantly lower risk of food allergies, there was a trend in that direction.)

As I have written about earlier, the recommendation to breastfeed exclusively for 6 months really only makes sense for women living in developing countries, where access to clean water and safe food sources can be limited. There are no demonstrated benefits for women living in developed countries like the US and the UK. It’s past time for medical organizations to reconsider this misguided blanket advice.


An early beta hCG test is a good predictor of an ongoing pregnancy

That first glimpse of two pink lines–is it real?–and your heart start to pound with excitement. You’re pregnant!

But after a few minutes of celebration, you descend back to earth. Okay, you’re pregnant, but for how long? Will this pregnancy stick?

You have entered a new, more hopeful limbo than the much bemoaned two-week wait. But this one still no picnic.

These kinds of worries are inevitable. Miscarriage is very common, especially early in pregnancy. And for most women, good info about viability does not come until the first ultrasound usually performed at 8-10 weeks.

Fortunately, women undergoing fertility treatments receive information about their chances a bit earlier with a “beta”–that is, a blood test of their beta hCG (Human Chorionic Gonadotropin) levels.

What is HCG (Human Chorionic Gonadotropin)?

The embryo produces hCG as it burrows into your uterine lining. HCG passes into your bloodstream and helps to maintain the uterine lining and keep progesterone levels high in early pregnancy.

During the first trimester, blood levels of HCG rises quickly, normally doubling every 48 hours in early pregnancy, until reaching a peak around 20 weeks, after which they begin a slow decline.

Predicting ongoing pregnancy with HCG

The level of hCG in your blood predicts your chances of an ongoing pregnancy–which researchers usually define as one that lasts through the first 8-12 weeks.

The table below summarizes findings from several IVF clinic-based studies which tracked pregnancy outcomes by hCG levels. These numbers apply to singleton pregnancies. Twin pregnancies tend to have higher hCG levels.

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When comparing your test results, pay close attention to the post-retrieval or post-transfer date listed in the Day tested column. Some studies report by day from egg retrieval (post retrieval). Others report from day after blastocyst or embryo transfer (post transfer). HCG rises rapidly in early pregnancy, so whether a specific beta is a positive or negative signs depends on precisely when hCG was measured.

The hCG threshold for likely viability rises with each day. As one research team that examined hCG levels on different days post-retrieval reported “hCG samples … were taken on day 14, 15 or 16 after oocyte retrieval in 204 patients undergoing IVF or ICSI were analyzed… optimal cut-off levels to discriminate between viable and non-viable pregnancies… were found at 76, 142 and 223 IU/L for day 14, 15 and 16, respectively”

Interpreting your betas

If your betas are above the numbers listed in the table above, congratulations! Your pregnancy has a very high chance of continuing through the first trimester.

Note, however, that HCG is not as good of an indicator of a live birth as it is of avoiding a first trimester miscarriage–so you’re not completely off the worry hook yet. Your first ultrasound will provide better information than your beta about your chances of a live birth.

What if your hCG is below those in the above table? Don’t panic. In all of these studies about 40-60% of the pregnancies with values below the stated thresholds were ongoing. In other words, hCG was better at predicting a good outcome than it was at predicting  a bad outcome. Because hCG levels vary a lot from pregnancy to pregnancy, there is no strict cutoff for determining viability.

HCG Levels during the first trimester

Normal HCG levels range widely in early pregnancy.

Below are the ranges of beta hCG by week following your Last Menstrual Period (LMP), according to the American Pregnancy Association.

  • 3 weeks LMP: 5 – 50 mIU/mL
  • 4 weeks LMP: 5 – 426 mIU/mL
  • 5 weeks LMP: 18 – 7,340 mIU/mL
  • 6 weeks LMP: 1,080 – 56,500 mIU/mL
  • 7 – 8 weeks LMP: 7, 650 – 229,000 mIU/mL
  • 9 – 12 weeks LMP: 25,700 – 288,000 mIU/mL
  • 13 – 16 weeks LMP: 13,300 – 254,000 mIU/mL
  • 17 – 24 weeks LMP: 4,060 – 165,400 mIU/mL
  • 25 – 40 weeks LMP: 3,640 – 117,000 mIU/mL

Serial hCG measurements

What does often indicate an impending miscarriage, however, are hCG levels that fail to double every 48 hours or that drop over time. This nearly always indicates a failing pregnancy. It can also indicate an ectopic pregnancy–an pregnancy that has implanted somewhere other than the uterus.

One final caveat: All of the above studies involved women undergoing IVF. We cannot say whether these numbers apply to women undergoing IUI or who conceived naturally.

Special case: Frozen embryo transfers

Some but not all studies find that HCG levels are lower and less predictive of miscarriage after frozen (as opposed to fresh) embryo transfers.

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In Xue’s 2014 study, nearly 100% of pregnancies that made it past 12 weeks had day 12 hCG levels about 50 IU/L, as shown in the table below. But many miscarriages also had hCG levels above this threshold; 50 IU/L did not discriminate well between ongoing pregnancies and miscarriages.

A higher threshold of 135-147 IU/L performed better. Nearly 94% of pregnancies with hCG levels above this threshold were ongoing.

Have you had a beta? What was it and how did your pregnancy turn out?

(If you have had a first trimester ultrasound, you may wish to check out my post on miscarriage risk by week, by fetal heart rate, and by other risk factors like your age.)


Porat S, E. al. Early serum beta-human chorionic gonadotropin in pregnancies after in vitro fertilization: contribution of treatment variables and prediction of long-term pregnancy outcome.

Kim, J. H. et al. Serum biomarkers for predicting pregnancy outcome in women undergoing IVF: human chorionic gonadotropin, progesterone, and inhibin A level at 11 days post-ET. Clin. Exp. Reprod. Med. 39, 28 (2012).

Kim, Y. J. et al. Predictive value of serum progesterone level on β-hCG check day in women with previous repeated miscarriages after in vitro fertilization. PLoS One 12, (2017).

Kumbak B, E. al. Serum oestradiol and beta-HCG measurements after day 3 or 5 embryo transfers in interpreting pregnancy outcome.

Papageorgiou TC, E. al. Human chorionic gonadotropin levels after blastocyst transfer are highly predictive of pregnancy outcome.

Xue Y, E. al. Effect of vitrification versus slow freezing of human day 3 embryos on β-hCG levels.

Ochsenkühn R, E. al. Predictive value of early serum beta-hCG levels after single blastocyst transfer.

Lambers MJ, E. al. Optimizing hCG cut-off values: a single determination on day 14 or 15 is sufficient for a reliable prediction of pregnancy outcome.

Sung N, Kwak-Kim J, Koo HS, Yang KM. Serum hCG-β levels of postovulatory day 12 and 14 with the sequential application of hCG-β fold change significantly increased predictability of pregnancy outcome after IVF-ET cycle. Journal of Assisted Reproduction and Genetics. 2016;33(9):1185-1194.

Back sleeping and stillbirth revisited: A reason for caution, or a few extra pillows

As longtime readers of my blog know, in 2011, carrying my first child, I became obsessed with the question of whether pregnant women could lie on their backs–either for short periods of time, such as during a yoga class, or while asleep at night.

Several OBs told me to avoid lying on my back. But their justifications were murky, and their advice conflicting. Not a one could point to a single published study backing this advice up. And when asked at what point in pregnancy I needed to start avoiding back sleeping, their answers were all over the place. One told me it was verboten from 4 months on, another from 5 months on, and the third claimed I should worry only in the last month or so.

Sleeping with a bowling ball-sized stomach is challenging, to say the least. At the same time, groundless sleep prohibitions with vague but terrifying warnings that you might harm your baby are immensely frustrating, and yet almost impossible to disregard.

But while in 2011, these dire warnings sounded like a yet another pregnancy prohibition in search of a reason (no Brie, not a drop of alcohol, keep your heart rate below 140 while exercising, etc., etc.), several studies (one from Australia, two from New Zealand, one from Ghana, and the latest, from the UK) have since found that back sleep may indeed be linked to what is termed late stillbirth, or pregnancy loss after 28 weeks.

The science of back sleeping and stillbirth

Continue reading Back sleeping and stillbirth revisited: A reason for caution, or a few extra pillows

Why is the American Academy of Pediatrics exaggerating the benefits of breastfeeding?

The AAP doubled down on the long-term benefits of breastfeeding, just as the evidence for those benefits was crumbling underneath their feet.

In their most recent statement on breastfeeding, issued in 2012, the American Academy of Pediatrics (AAP) reaffirmed their earlier guidelines recommending 6 months of exclusive breastfeeding. They justified this recommendation by citing “the health outcomes of exclusively breastfed infants and infants who never or only partially breastfed”.

In effect, the AAP doubled down on the idea breastfeeding confers massive, lifelong benefits to babies–benefits so profound, they say, that the decision to breastfeed should not be considered a “lifestyle” choice but in “investment” in your child’s future–just as recent, large, and better-designed studies have overwhelmingly shown that the benefits of breastfeeding in the developed world are trivial.

Continue reading Why is the American Academy of Pediatrics exaggerating the benefits of breastfeeding?

Sign away mamas: Formula consent forms are based on unscientific fearmongering

As part of their “baby-friendly” initiatives, some hospitals now require women to sign consent forms before receiving formula. These forms purport to list the “harms” associated with “a single bottle” of formula, and ask that parents signify their understanding that formula should not be given unless medically necessary.

On its face, asking parents to sign a waiver to receive formula, a long-used and widely available way of feeding babies, seems astoundingly paternalistic. But what I find most shocking are the allegedly “scientific” claims these forms make about supplementing with formula.

Continue reading Sign away mamas: Formula consent forms are based on unscientific fearmongering

Five little known facts about pregnancy weight gain

Even for the most body-secure among us, gaining anywhere from 20 to 40 pounds during pregnancy is no picnic. Sure, we have days where we are full of energy and glowing and ready to flaunt our adorable baby bumps. But we also have days, especially in the third trimester, where we feel less like mama-goddesses and more like sweaty, frumpy, nothing-fits-anymore messes.

To take the edge off, I turned to the Institute of Medicine’s (IOM) report on pregnancy weight gain, which provides the evidence base for their widely-referenced weight gain guidelines:

  • Underweight: Gain 28-40 pounds
  • Normal weight: Gain 25-35 pounds
  • Overweight: Gain 15-25 pounds
  • Obese: Gain 11-20 pounds

Some of what I learned from their report was outright reassuring, like that a sudden bump up in weight in the second trimester is common and does not imply that you will continue to gain weight at a fast clip. Other facts, like that 15-30 percent of the fat gained during pregnancy goes straight to our thighs, were less reassuring. Continue reading Five little known facts about pregnancy weight gain

What’s the deal with the infant microbiome?

The human microbiome is one of the hottest topic in medical research today, and with good reason.

This collection of trillions of microscopic inhabitants–bacteria, viruses, and fungi—cover nearly every interior and exterior surface of the human body, and many scientists now believe that these unseen co-passengers, far from being incidental hangers-on, are instead actively cultivated by our bodies and play a critical role in our immune and metabolic health.

Over the last decade, studies have linked the composition of our microbiomes the to a panoply of modern ailments: obesity, asthma, allergies, acne, C difficile induced diarrhea, and autoimmune diseases like Crohn’s and Type 1 Diabetes.

Our microbiome may matter most in early infancy.

Continue reading What’s the deal with the infant microbiome?

Surviving the First Year: Two books to help you understand baby’s sleep

For most new parents, sleep becomes an obsession, their most precious commodity. They will happily trade exercise, sex, and time with friends for just a shot at catching some Z’s–kind of like how a rat with ad libitum access to cocaine will happily forgo food.

Continue reading Surviving the First Year: Two books to help you understand baby’s sleep

Overwhelmed by prenatal genetic testing options? Download my ebook!

Who needs prenatal testing for genetic disorders? How much does your risk of carrying a baby with a genetic disorder increase with your age? Which prenatal test or screen is right for you?

These are among the questions my amazing co-author Molly Dickens (and fellow pregnant scientist blogger/partner-in-crime) and I tackle in our new ebook on prenatal testing. We provide a quick “cheat sheet” on how these tests compare, and then dig into the nitty-gritty details of each as well as the history of prenatal testing and how to estimate your personal risk of carrying a baby with a genetic disorder.

Continue reading Overwhelmed by prenatal genetic testing options? Download my ebook!

Prenatal Testing: Download my ebook (free)!

Who needs prenatal testing for genetic disorders? How much does your risk of carrying a baby with a genetic disorder increase with your age? Which prenatal test or screen is right for you?

These are among the questions my amazing co-author Molly Dickens (and fellow pregnant scientist blogger/partner-in-crime) and I tackle in our new ebook on prenatal testing. We provide a quick “cheat sheet” on how these tests compare, and then dig into the nitty-gritty details of each as well as the history of prenatal testing and how to estimate your personal risk of carrying a baby with a genetic disorder.

Even having gone through prenatal testing twice before, I was still surprised to learn while researching this book that…

  1. Testing only women over 35, as was the case in the 80s and early 90s, misses around 70% of the cases of Down’s Syndrome.
  2. The risk of miscarriage from amnio and CVS is around 1 in 1000–far, far lower than the still commonly cited but outdated 1 in 100 estimate.
  3. Until you are 38 years old, you are more likely to carry a baby with a chromosomal disorders involving tiny pieces of chromosomes than carry a baby with disorder involving missing or extra whole chromosomes–but these disorders are not well detected by any prenatal screens. This is a huge problem, because younger women are often advised to get screens over diagnostic testing.
  4. How women under 35 are more than twice as likely to get a false alarms on prenatal screens as women over 35.

And so much more that I am excited to share.

We all need to up-to-date, evidence-based information to make the best decisions for us and our families. But with prenatal testing rapidly evolving, sometimes doctors and other healthcare professionals are woefully behind or outright misinformed on the latest developments. So please download and share with fellow parents-to-be!

Download the pdf here: Prenatal Testing ebook.

How much iron does my baby need?

Too little iron in infancy can cause irreversible cognitive deficits. And iron deficiency can have no symptoms. It’s scary.

Yet the advice parents get on meeting your baby’s iron needs is complex, conflicting, and incredibly confusing.

Continue reading How much iron does my baby need?

Breast may be best, but why isn’t it better?

In honor of World Breastfeeding Week (yes, yes, I know–it ended yesterday), we need to talk about a widely overlooked aspect of breastfeeding, its recipients!

Nope, I am not talking about our babies. (After all, who could overlook them?) I am talking about our babies’ gut bacteria.

Breast milk contains carbohydrates (known as HMOs, for Human Milk Oligosaccharides) specially designed to nourish specific gut bacteria, particularly Bifidobacteria. Bifidobacteria contain genes designed to metabolize HMOs–implying they have co-evolved with us for a long time.

This process of seeding your baby’s gut begins not with breastfeeding, though, but before birth. During pregnancy, women’s bodies cultivate these bacteria while pruning out others, seemingly in preparation to pass them onto our babies during birth.

Why does this matter? Health benefits.

Breastfeeding may benefit health indirectly–by cultivating the right gut bacteria. Scientists now believe that having the right balance of gut bacteria helps to calibrate your baby’s immune system and metabolism, possibly with lifelong effects.

I dig into the latest research on this breastfeeding-gut-health axis in my latest post for BloomLife. Check it out!…

Drinking While Nursing: 7 Things to Know

While over half of mothers in the U.S. drink alcohol while breastfeeding, many of us are foggy on how this does (or does not) affect our babies.

Can you drink a glass of wine while breastfeeding your baby? Or do you need you wait 2-3 hours for the alcohol to clear? And exactly how much alcohol is too much alcohol to nurse?

Doctors and trusted sources like KellyMom and Babycenter give wildly conflicting advice on these points.

Continue reading Drinking While Nursing: 7 Things to Know

A quick update and where to check out some of my latest writing elsewhere on the web

As you may have noticed, it has been a while since I have posted on this blog. Rest assured, I have a ton of great content in the works.

But what has been keeping me too busy to post and up at night? Well, Baby #3 for starters. (Now 8 months! How time flies… or with a new baby, how it passes in slow motion and sudden leaps.)

And in my stolen moments (read:naps) I have been writing content for a company called BloomLife. BloomLife makes a contraction tracker, just like those used in a hospital but for at home use. It syncs with your phone and lets you know if you are experiencing contractions, how strong they are, and how long they last.

Baby #3 and her big sister. None of us were quite ready to wake up the morning this picture was taken. Yet there we were, up.

Many of my posts for Bloom will be of interest to my readers, so I wanted to share them with you here. Hop on over and check them out!

  • Prenatal Genetic Testing and Screening. My take on the new kid on the prenatal genetic screening block, Non-Invasive Prenatal Testing (NIPT) and why it needs to be offered to all women, not just women over 35.
  • Stalled Labor. My first labor was going gangbusters until I arrived at the hospital, where it swiftly ground to a halt. This is a common birthing experience. At the time, I blamed the slowdown on stress, but another unexpected culprit may have been to blame: those glaring florescent hospital lights. Here’s more on how humans evolved to labor at night, and why laboring women would be wise to dim those darn lights!
  • Exercise during pregnancy. Should you avoid starting a new exercise program while pregnant? Do you need to keep your heart rate below 140? Will lifting weights prompt preterm labor? Contrary to what you may have heard, the answer to all of these questions is an emphatic NO. I discuss the all these exercise myths here, and talk about the latest research and recommendations on exercise for pregnant women.
  • Natural Remedies for Group B Strep. Anywhere from quarter to a third of pregnant women test positive for Group B Strep (GBS) in their third trimester. In the U.S., this means receiving IV antibiotics during labor, to prevent early-onset Group B Strep, a serious but rare infection that occurs when a newborn contracts GBS during birth. But nobody wants to receive antibiotics if they can avoid it, especially during birth, when mom needs to pass her microbiome–a diverse collection of healthy bacteria and other microbes–to her baby. So, is there anything you can do to avoid testing positive? I talk about the research on vinegar rinses, yogurt squatting, and probiotics here.

What I’ve Been Doing the Last Few Weeks

It’s been awhile since I’ve posted on this blog, so I wanted to give my readers a bit of an update on what I’ve been up to these past couple of months.

Mostly I’ve been away because of some good news: I’m expecting our third child, a girl, coming sometime in October!

Continue reading What I’ve Been Doing the Last Few Weeks