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The critical development period ends
Pregnancy

The critical development period ends

2 min readWeek 13
Key takeaways
2 min
  • Celebrate reaching the end of the critical development period when major health threats to your baby significantly decrease.
  • Manage common pregnancy symptoms like constipation, heartburn, and headaches with doctor-approved treatments and dietary changes.
  • Gain approximately one pound per week during the first 20 weeks if expecting twins to prevent low birth weight.
  • Increase iron-rich foods and double your liquid intake when carrying multiples to support your expanded circulatory system.
  • Monitor vaginal discharge for changes and consult your doctor about any spotting after intercourse or exams.

The critical development period ends around week 12-13 of pregnancy, significantly reducing health threats to your baby. After this milestone, expectant mothers typically feel better physically and emotionally as major organ development completes.

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The critical development period ends

After this week of pregnancy, there are fewer threats to the health and development of the baby; the path ahead is clearer! Many expectant mothers begin to feel better both physically and emotionally. Most unpleasant pregnancy-related ailments are minor and easily treated, these can include:

  • Constipation: Digestion slows down during pregnancy, which can lead to constipation. While it might not be severe, you may still want to consult your doctor on possible dietary changes which can help make you more regular [1].

  • Heartburn: The hormone progesterone, abundant in healthy pregnancies, relaxes tissues, including the valve between the stomach and the esophagus. As a result, stomach acid rises into the esophagus, causing irritation, a burning sensation, and an unpleasant taste in your mouth.

  • Headache: Usual painkillers used to treat headaches are not all approved or safe for use during pregnancy, so ask your doctor about the approved choices. In case of severe or recurring headaches or seizures, see your doctor immediately [2].

If you are expecting twins

Now you know where your increased hunger was coming from! With a multiple pregnancy, mom needs a lot of extra calories. Doctors believe that a woman expecting twins should gain about half a kilo (around a pound) a week during the first 20 weeks so that the twins are not born underweight [3]. This is especially important if your BMI before pregnancy was below 18.5.

Your circulatory system has to provide for not just one, but two babies. And maybe even supply blood to two placentas. Therefore, you will have to consume more iron rich foods and likely supplements. You should also increase your liquid intake to twice as much as before pregnancy [4].

Discharge

At this point, normal vaginal discharge should not change from the previous week. It should be light in color, even, and may have a slightly sour smell. If you see spotting after intercourse or a gynecological exam, consult your doctor.


Frequently asked questions

The critical development period typically ends around week 12-13 of pregnancy. After this point, there are fewer threats to your baby's health and development, and most major organs have formed.

Women expecting twins should gain about half a kilogram (1 pound) per week during the first 20 weeks. This helps ensure the babies are not born underweight, especially if your pre-pregnancy BMI was below 18.5.

Not all usual painkillers are safe during pregnancy. Always consult your doctor about approved headache treatments. Seek immediate medical attention for severe or recurring headaches.

Pregnancy slows digestion leading to constipation. Consult your doctor about dietary changes that can help regulate bowel movements. They may recommend increased fiber intake and adequate hydration.

Normal vaginal discharge during pregnancy should be light in color, consistent, and may have a slightly sour smell. Contact your doctor if you notice spotting after intercourse or gynecological exams.

Medical Disclaimer

This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or qualified health provider with any questions you may have regarding a medical condition.

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Medically reviewed content

Reviewed by healthcare professionals · Updated June 7, 2025

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