Emily Oster

4 min Read Emily Oster

Emily Oster

How Long Should I Wait Before Having Another Kid?

Q&A on birth spacing

Emily Oster

4 min Read

I’m having difficulty finding info on the risks/benefits of different interpregnancy intervals. The American College of Obstetricians and Gynecologists (ACOG) recommends counseling “about the risks and benefits of repeat pregnancy sooner than 18 months” and then cites several articles, none of which I can access. When I asked my OB-GYN NP, she just said, “We don’t recommend shorter than 18 months.” But why? What is the quality of the studies? I get that less than six months is not great, but is a 12-month interval just as bad? As someone who hopes to have more children, how do I balance the risks of being pregnant once or twice over age 35 with risks due to having a shorter interpregnancy interval? What even are the risks to current and potential offspring or to me?

—Begging for more data

Your last point here strikes me as the most important one to consider. So often in pregnancy, we think of there being some default “safe” option. But as you point out, there often isn’t! Either you’re having too short a birth interval or you’re stepping into the dreaded Advanced Maternal Age. Is it better to have two kids 23 months apart or be an “elderly multigravida” (yes, that’s a thing)?

The WHO recommends at least two-year spacing between children (this would be, in fact, about a 15-month minimum interpregnancy interval). This is based on studies like this JAMA meta-analysis, which ACOG references and which I accessed. That paper finds an increase in risk of preterm birth, small size for gestational age, and low birth weight for pregnancy intervals shorter than 18 months. These effects are very large for an interval less than six months and quite small for the intervals longer than that.

A central issue, though, is that this meta-analysis includes a lot of studies from developing countries. In resource-poor settings, there is much more reason to think that the depletions of pregnancy would take longer to recover from. A short interpregnancy interval can increase risks of anemia and malnutrition, which make later pregnancies riskier. However: these issues are just much less of a concern in places where food security is more universal.

When the discussion is limited to higher-resource settings, any links become more tenuous, and to the extent that one sees any negative impacts, it is only for intervals of less than six months between pregnancies. Moreover, even these effects may be driven by differences across women. Perhaps the best study of this uses birth registry data, which allows for comparisons within women, looking at women with multiple birth intervals, some longer and some shorter. When comparing across women, that study finds that interpregnancy intervals less than six months are associated with increased preterm birth risk, but the same is not true when they look within mothers. (They do find that these very short intervals increase the risk of obesity at the start of the next pregnancy and of gestational diabetes.)

What if you had a C-section? Data suggests that the risk of complications from an attempted vaginal birth is higher if you get pregnant again within six months. But again, the compelling data here is on these very short intervals, not the longer ones.

Putting this together: in high-resource settings, the evidence for risks even of very short pregnancy intervals is relatively limited. These studies do not consistently suggest there would be risks to a pregnancy interval of 12 months, or 15 months.

A reasonable question to ask is: Why is 18 months quoted? One possible reason is that in many of these studies, the groupings of interpregnancy intervals are <6 months, 6-11, 12-17, 18-23, and then longer. Usually 18-23 months is the reference group, so everything else is compared to that. When we say the risks are higher for <6 months, it is compared to that reference. I do wonder whether, then, that reference takes on a particular meaning that is not supported in the data. As in, what if the grouping was 12-15 months and 16-23? Would you then be told not less than 16 months? We’ll never know! But for now, the data on waiting suggests you do not need to.

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👉Comment “Link” for a DM to an article that summarizes all of the best potty training advice we collected. 

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👉Comment “Link” for a DM to an article that summarizes all of the best potty training advice we collected.

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Today is the first episode of a new biweekly series on my podcast: Late-Night Panic Google. On these mini-episodes, you’ll hear from some familiar names about the questions keeping them up at night, and how data can help. First up: @claireholt!

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☀️ Keep them in the shade as much as possible when you’re out.
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Comment “Link” for a DM to an article on the data around sun and heat exposure for babies.

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OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio! ...

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio!

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio! ...

OUT NOW: My new book “The Unexpected: Navigating Pregnancy During and After Complications” is available on April 30th. All of my other books came out of my own experiences. I wrote them to answer questions I had, as a pregnant woman and then as a new parent. “The Unexpected” is a book not to answer my own questions but to answer yours. Specifically, to answer the thousands of questions I’ve gotten over the past decade from people whose pregnancies were more complicated than they had expected. This is for you. 💛 Order now at my link in bio!

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Is side sleeping important during pregnancy? Comment “Link” for a DM to an article on whether sleep position affects pregnancy outcomes.

Being pregnant makes you tired, and as time goes by, it gets increasingly hard to get comfortable. You were probably instructed to sleep on your side and not your back, but it turns out that advice is not based on very good data.

We now have much better data on this, and the bulk of the evidence seems to reject the link between sleep position and stillbirth or other negative outcomes. So go ahead and get some sleep however you are most comfortable. 💤

Sources:
📖 #ExpectingBetter pp. 160-163
📈 Robert M. Silver et al., “Prospective Evaluation of Maternal Sleep Position Through 30 Weeks of Gestation and Adverse Pregnancy Outcomes,” Obstetrics and Gynecology 134, no. 4 (2019): 667–76. 

#emilyoster #pregnancy #pregnancytips #sleepingposition #pregnantlife

Is side sleeping important during pregnancy? Comment “Link” for a DM to an article on whether sleep position affects pregnancy outcomes.

Being pregnant makes you tired, and as time goes by, it gets increasingly hard to get comfortable. You were probably instructed to sleep on your side and not your back, but it turns out that advice is not based on very good data.

We now have much better data on this, and the bulk of the evidence seems to reject the link between sleep position and stillbirth or other negative outcomes. So go ahead and get some sleep however you are most comfortable. 💤

Sources:
📖 #ExpectingBetter pp. 160-163
📈 Robert M. Silver et al., “Prospective Evaluation of Maternal Sleep Position Through 30 Weeks of Gestation and Adverse Pregnancy Outcomes,” Obstetrics and Gynecology 134, no. 4 (2019): 667–76.

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I co-wrote #TheUnexpected with my friend and maternal fetal medicine specialist, Dr. Nathan Fox. The unfortunate reality is that about half of pregnancies include complications such as preeclampsia, miscarriage, preterm birth, and postpartum depression. Because these are things not talked about enough, it can not only be an isolating experience, but it can also make treatment harder to access.

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#pregnancy #pregnancycomplications #pregnancyjourney #preeclampsiaawareness #postpartumjourney #emilyoster
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#tylenol #pregnancy #pregnancyhealth #pregnancytips #parentdata #emilyoster

Exciting news! We have new, high-quality data that says it’s safe to take Tylenol during pregnancy and there is no link between Tylenol exposure and neurodevelopmental issues in kids. Comment “Link” for a DM to an article exploring this groundbreaking study.

While doctors have long said Tylenol was safe, confusing studies, panic headlines, and even a lawsuit have continually stoked fears in parents. As a result, many pregnant women have chosen not to take it, even if it would help them.

This is why good data is so important! When we can trust the data, we can trust our choices. And this study shows there is no blame to be placed on pregnant women here. So if you have a migraine or fever, please take your Tylenol.

#tylenol #pregnancy #pregnancyhealth #pregnancytips #parentdata #emilyoster
...