Intrauterine pregnancy is when a fertilized egg implants and grows in the correct place – your uterus. Not all early pregnancies develop typically. An ultrasound is the only way to confirm that implantation occurred in the right place.
Pregnancy is a remarkable journey starting with the fertilization of an egg and implantation. Every early sign and symptom of pregnancy can be exciting but also raise many questions.
How do you know if your pregnancy is developing in the right place? Ultrasound is your answer.
There are many aspects of intrauterine pregnancy to explore, including stages of pregnancy, what you can expect, and the risks during early pregnancy.
An intrauterine pregnancy is when a fertilized egg travels down the fallopian tube and implants in the lining of your uterus. Here it grows and develops from an embryo to a fetus and, finally, a baby.
If the pregnancy is not in your uterus, it’s ectopic. According to the American Society for Reproductive Medicine, an ectopic pregnancy occurs in 1–2% of all conceptions.
Ectopic pregnancies cannot survive. If a pregnancy becomes ectopic, you will need immediate medical treatment. Treatment for ectopic pregnancy is generally medication or surgery.
If an ectopic pregnancy progresses too far, the embryo can grow too big, causing a fallopian tube to rupture. This is a medical emergency because there may be significant internal bleeding. Early treatment can prevent more serious complications.
Learn more about ectopic pregnancy, how one is diagnosed, and the treatment options.
Early pregnancy comes with many signs and symptoms, including:
- missing a menstrual period
- a positive pregnancy test
- tender breasts or nipples
- food aversions
- food cravings
- frequent urination
- mood changes
None of the symptoms confirm that your pregnancy is in your uterus and not ectopic. Symptoms of an ectopic pregnancy to watch for include:
An ultrasound done with a probe in your vagina called a transvaginal ultrasound will show a fluid-filled sac (gestational sac) around the embryo in your uterus as early as
Ultrasound is the only way to confirm that you have an intrauterine pregnancy.
Experts calculate pregnancy in days and weeks. A full-term pregnancy is 40 weeks or 280 days from the first day of your LMP. During the first 2 weeks, you’re not even pregnant.
Most people use months or trimesters to describe the stages of pregnancy.
The first trimester is from the first day of your LMP through 12 weeks. Your egg fertilizes and implants in your uterus during this time. All the major organs develop.
You can expect the following signs and symptoms:
- menstrual periods stop
- tender breasts and nipples
- enlarged breasts
- nausea and vomiting
- food cravings and aversions
- more frequent peeing
You may even lose a few pounds.
The second trimester lasts from 13–27 weeks. Your fetus grows and develops rapidly.
You may experience the following:
- improvement to nausea and vomiting
- increased appetite
- increased energy
- your abdomen expands as the uterus grows
- feeling fetal movement
- the skin on your abdomen feels tight and may get stretch marks
- darkening of the skin around your nipples
- possible brown patches on your face
The third trimester is measured from 28 weeks until delivery, around 40 weeks. During this time, your fetus gains weight, and their organs mature.
You can expect:
An intrauterine pregnancy is the desired and most common type of pregnancy. But some pregnancies cannot survive or are called nonviable.
If you have any of the following situations, the pregnancy is nonviable and requires medical attention:
- Chemical pregnancy: A chemical pregnancy happens when a fertilized egg does not implant properly.
- Blighted ovum: A blighted ovum happens when a fertilized egg stops developing after a gestational sac forms in the uterus.
- Ectopic pregnancy: An ectopic pregnancy happens when a fertilized egg implants outside the uterus, most often in a fallopian tube.
- Spontaneous abortion or miscarriage: A spontaneous abortion or miscarriage happens when an intrauterine pregnancy stops developing, and your body expels it from the uterus before 20 weeks.
- Missed abortion: A missed abortion happens when an embryo or fetus is without heart activity, and a miscarriage does not spontaneously happen.
- Molar pregnancy: In a molar pregnancy, a tumor develops in the uterus early in pregnancy because of a genetic error.
- Stillbirth: A stillbirth is the loss of a pregnancy after 20 weeks.
While not all of these are preventable, you can work closely with your OB-GYN on your pregnancy care to ensure you’re doing everything possible to maintain a healthy pregnancy.
If I’ve had an ectopic pregnancy before, what are the chances of it happening again?
Ectopic pregnancies can happen again, but there’s no sure thing. Evidence suggests that if you’ve had one, your chance of it happening again is
If you’ve had an ectopic pregnancy, reach out to your doctor if you’re concerned about a future one.
What can I do to increase my odds of having an intrauterine pregnancy?
Most importantly, prevent or treat sexually transmitted infections (STIs) like chlamydia. Infections can cause scarring in your fallopian tubes.
Not smoking will also increase the likelihood of implantation occurring in your uterus.
Can I have a healthy pregnancy after having a pregnancy loss?
Yes, most women who have had a pregnancy loss can go on to have a healthy intrauterine pregnancy.
Factors such as the cause of the previous pregnancy loss and underlying health conditions affect the likelihood of a successful future pregnancy. Each person’s situation is different.
Intrauterine pregnancy occurs when a fertilized egg implants inside of your uterus. An ultrasound will confirm that your pregnancy has indeed happened in your uterus.
With healthy implantation, the embryo develops and grows. Pregnancy has three stages called trimesters. Each trimester has joys and challenges.
Because of the many risks associated with pregnancy, it is vital to have regular prenatal care.