What is the stable trimester of pregnancy? How to spend it and about NIPT【supervised by doctor】

Summary of this article

The stable period of pregnancy is a time when symptoms such as morning sickness and fatigue are more stable than in the early stages of pregnancy. It is advisable to spend the stable period of pregnancy exercising frequently, preparing supplies for the baby and attending parent-teacher classes.

The gender of the fetus is known at 10 weeks.

What is the stable period of pregnancy?

The term ‘stable pregnancy’ refers to a period when symptoms such as morning sickness and fatigue are more stable than in early pregnancy.

When you reach the stable trimester, the placenta is complete and the hormonal balance is stable. In conjunction with this, the body temperature returns to normal, so many women experience less lethargy and feverishness in the early stages of pregnancy.

There was also a risk of ‘early miscarriage’ in the early stages of pregnancy, but this risk is reduced and both mother and child are stable at this stage.

During the stable phase of pregnancy, the abdomen becomes noticeably fuller

As everyone’s physical condition is unique, there is no strict ‘when is the stable period of pregnancy’. Generally, the period between 16 and 32 weeks of pregnancy is known as the stable period of pregnancy.

From around 16 weeks’ gestation, the belly gradually becomes noticeably fuller. This is because the uterus is about the size of an adult’s head and grows closer to the belly button.

However, at around 16 weeks’ gestation, the belly bulge is surprisingly not noticeable if you are wearing clothes.

When the belly bulges are around this size, the ‘fundal length of the uterus’ can be measured. This measurement of the fundal length of the uterus shows the length from the apex of the uterus to the top of the pubic bone.


Different number of weeks from ‘mid-pregnancy’

A similar term to the stable trimester of pregnancy is the ‘mid-term pregnancy’. This concept of the mid-term pregnancy divides the 10-month gestation period as follows.

  • Early pregnancy: up to 13 weeks 6 days
  • Mid-term pregnancy: 14 weeks 0 days – 27 weeks 6 days
  • Late pregnancy: 28 weeks onwards

As such, the number of weeks differs slightly from the stable stage of pregnancy, so care should be taken not to confuse the two.

To begin with, the term ‘stable pregnancy’ is not an official medical term.

Fetal movements start to occur when the pregnancy enters the stable phase

From about 16 weeks, when the pregnancy enters the stable phase, you will start to feel fetal movements.

Of course, this also varies from person to person.

Some first-time mothers start to feel fetal movements at around 20 weeks.

From this time onwards, you will be more aware of your baby.

Try to stay as stress-free as possible and communicate with your baby by patting her belly and talking to her.

What are the differences between symptoms in early and stable pregnancy?

The following symptoms may occur in early pregnancy.

  • Morning sickness
  • Get irritated
  • Bleeding separate from menstruation
  • Feverish
  • General malaise
  • Drowsiness
  • Abdominal pain
  • Frequent urination
  • Gastric nausea

These symptoms occur frequently in pregnancy.

If your menstruation is a week or so later than expected and your temperature is high, the chances of pregnancy are even higher.

These symptoms can lead to mental and physical instability, such as severe morning sickness, inability to eat and irritability due to ill health.

However, once you enter the stable phase of pregnancy, these symptoms will relatively calm down.

What are the possible symptoms of a stable pregnancy?

In the stable phase of pregnancy, the early symptoms described above decrease.

However, it is important to note that there are other symptoms that are unique to the stable phase of pregnancy.

  • Anaemia
  • Constipation
  • Lumbago
  • Skin trouble
  • Palpitations and shortness of breath

During pregnancy, the number of red blood cells is low in relation to blood volume.

This makes you more prone to anaemia, so eat green and yellow vegetables, red meat, soya and clams for iron.

It is also effective to take vitamin C together.

Back pain is caused by bending at the waist to support the growing belly.

It is recommended to avoid bending at the waist as much as possible and to be aware of your back muscles.

Depending on the pregnant woman’s condition, morning sickness may return.

Of course, the above physical conditions are only a guide.

Even in the stable phase of pregnancy, the risk of miscarriage is not completely zero, and some pregnant women experience a return of morning sickness.

This area varies from person to person, so you should not let your guard down even if you have entered the stable trimester of pregnancy.

If you have any concerns about your anxiety or physical condition, do not hesitate to discuss them with your obstetrician.

Don’t panic if you feel an upset stomach during the stable phase of pregnancy

Many pregnant women are concerned about their health even during the stable phase of pregnancy, as morning sickness can return.

However, there is no need to worry about ‘upset stomach’.

Again, this varies from person to person, but you may feel a tummy tightness when you reach 17 weeks’ gestation.

This is caused by contractions of the uterus.

There is no need to worry about this as it is a natural occurrence, just like menstrual phenomena.

If you feel your abdomen is upset, lie down and it will go away naturally.

However, if you experience regular tummy contractions several times an hour, you should consult your obstetrician/gynecologist as there is a possibility of an imminent premature miscarriage.

To prevent an upset stomach in advance, observe the following three points.

  • Avoid excessive exercise
  • Avoiding stress
  • Warm oneself

Be alert for an upset stomach with pain and bleeding!

Thus, basically, there is no need to worry too much about the upset stomach itself.

However, if you feel pain or bleeding from the genitals when your abdomen is upset, you should be careful.

An upset stomach with pain or bleeding often occurs in the second trimester of pregnancy and may indicate the onset of conditions such as premature labour or premature separation of the normal placenta.

In this case, see a doctor immediately.

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NIPT should be performed before the stable trimester!

NIPT is a test based on blood samples taken from pregnant women to determine the baby’s risk of Down’s syndrome and other conditions.

NIPT at Hiro Clinic can be performed from the 10th week of pregnancy onwards.

The test is used to relieve prenatal anxiety in pregnant women, as it provides advance knowledge of disease risk by checking for chromosomal abnormalities.

The reason for this number of weeks is that a definitive test may be performed based on the test results.

The ideal time for a definitive test is up to around 17 weeks.

For NIPT, blood is drawn from the pregnant woman’s arm, so chromosomes can be tested safely and accurately without the risk of miscarriage.

The risk of disease and other risks identified by this NIPT cannot be confirmed as ‘absolutely this will happen’.

It is only a test to determine how likely it is to carry the disease.

What is important is that you know about the high risk of disease that the foetus carries and then ask, “What preparations are you going to make?” This means.

If there is an unwanted outcome, you will need time to discuss this with your family.

If necessary, preparations must also be made.

To deal with such situations in good time, NIPT should be performed early, before the pregnancy is stabilised.

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How to spend the stable period of pregnancy

When a woman enters the stable phase of pregnancy, as mentioned earlier, the placenta is completed and the baby is well nourished.

In conjunction with this, the stable period also stabilises the pregnant woman’s physical condition, such as when morning sickness subsides.

Therefore, she can gradually return to her normal life, but it does not mean that the risk of miscarriage is zero now that she is in the stable period.

It is necessary to continue to take care of your health condition.

Specifically, you should try to spend time in the following ways.

What is the stable trimester of pregnancy? How to spend it and about NIPT【supervised by doctor】

Exercise frequently

During the stable phase of pregnancy, you should exercise frequently.

When you enter the stable trimester of pregnancy, many people are instructed by their obstetrician, midwife or other health professional to exercise to avoid gaining too much weight and to be physically active.

It is true that most pregnant women’s physical condition stabilises during the stable phase of pregnancy.

Therefore, while their physical condition is stable, they should exercise to build up their pre-natal fitness and maintain their weight.

However, the risk of miscarriage does not disappear just because you have entered the stable period of pregnancy.

Some people continue to experience physical discomfort.

Many pregnant women enjoy their maternity life, but the timing of this varies from person to person. Therefore, there is no need to force yourself to exercise when you are not feeling well.

Try to stay as relaxed as possible.

If you are in a fit state to exercise, you can make use of the following to get moving.

  • Walking
  • Maternity swimming
  • Maternity yoga

As for yoga, some events are organised by municipal health centres.

Especially during pregnancy, pregnant women are prone to weight gain.

Excessive weight gain can lead to the risk of the following diseases, which should be carefully monitored

Gestational diabetes mellitus

Pregnancy hypertension

Of course, as explained earlier, the pregnant woman’s physical condition is paramount.

Excessive exercise should not be undertaken.

If you are experiencing signs of impending premature labour or other problems, always follow your doctor’s instructions on exercise.


Preparing to welcome your baby

During the stable phase of pregnancy, you can move your body to a certain extent, so you should prepare supplies for your baby.

It is important to make preparations during this period, as it is physically difficult to move when the birth is approaching.

Specifically, the following preparations should be made.

  • Baby clothes
  • Beds and baby baths
  • (Find a hospital with reasonable birthing facilities (e.g. if you want a pain-free delivery)
  • Find out about maternity grants
  • Visiting a nursery school

Participate in parent-teacher classes

‘Parents’ classes’ are classes organised by local authorities for parents of unborn children.

In these parent-teacher classes, you will be taught.

  • How pregnant women spend their time
  • What pregnant women usually take care of
  • How to proceed with childbirth
  • How to look after your baby
  • Maternity yoga (swimming) experience

This is a great opportunity to speak directly with an obstetrician or midwife and to address any concerns or worries that pregnant women may have.

Some parent-teacher classes also offer the opportunity to wear a ‘pregnancy jacket’ to experience the weight of an expectant mother’s stomach.

The same experiences as pregnant women will help you to bond more with your partner.

Taking maternity photos

Pregnancy is a period of life that is not often experienced.

That is why it is a good idea to take photos of the changes in your body with your partner, so that you can keep them as a memory.

During the photo shoot, the pregnant woman’s physical condition is also taken care of.

It is safer to take the photographs during the stable phase of pregnancy, before the approaching birth.

Consult with family members

Some people may decide to return home once to give birth and ask their parents to help with childcare.

If this is the case, discuss with your family how long you will be away from home.

If you are going back home, it is essential to check what kind of medical system is in place around your parents’ home.

As mentioned earlier, just because you are in the stable phase of pregnancy does not mean that you are always in perfect physical condition. There can be sudden changes in condition.

It is essential to be prepared for such contingencies.

If necessary, ask your doctor to write a letter of referral.

It is important to pass on to the expectant mother any special information about the birth.

Families should also discuss how to deal with the unwanted results of the NIPT mentioned earlier.

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What should pregnant women be aware of during the stable phase of pregnancy?

Pregnant women in the stable phase of pregnancy need to be aware not only of how to refresh themselves, but also of what to be aware of during this period.

Some of the things to be aware of during the stable trimester of pregnancy are listed below.

Be very careful when travelling and other excursions

If you are in the stable phase of pregnancy, it is safe to travel.

However, it is essential to take into account that you will be travelling for a long period of time.

For example, the blood clotting system is increased during pregnancy and blood clots can easily form.

It is therefore essential to take frequent breaks.

When travelling by car or train, it is easy to become sedentary, so deliberate physical exercise should be taken to avoid blood clots as much as possible.

When flying, some airlines require a doctor’s certificate for boarding.

Be sure to check this.

In addition, it is advisable to prepare the following in case of emergency.

  • Maternity health record book
  • Medicines prescribed by a doctor
  • Health insurance card

Pregnant women’s physical condition is a top priority when having sex

It is safe to engage in sexual activity if you are in the stable phase of pregnancy.

Be careful not to put pressure on your abdomen during pregnancy, as it will be larger.

If you feel an upset stomach or bleeding during sex, always stop the activity immediately and seek medical attention if necessary.

A simple upset stomach is fine, but if it continues for a long time, you need medical attention.

Also, never engage in sexual activity when there is a possibility of impending premature labour.

Condoms should also always be worn during pregnancy, as the pregnant woman’s immune system is compromised.

If you have sex without a condom and the foetus becomes infected, there is no way to recover.

Thus, it is absolutely necessary to be more concerned about the pregnant woman’s physical condition than in her normal sexual life.

Pregnant women should not force themselves to refuse if they do not feel comfortable or if they are not in good physical condition.

The partner should be aware of the pregnant woman’s feelings and physical condition and not force her to do so.

Prepare for hospitalisation just in case

Even if you are in the stable phase of pregnancy, you may suddenly fall ill.

Therefore, prepare for hospitalisation just in case.

It is a good idea to prepare the following.

  • Maternity health record book
  • Postnatal panties (postpartum panties)
  • Maternity pads (postpartum napkins)
  • Nursing bra
  • Towels and bath towels
  • Facial tissues
  • Facial cleansing products
  • Slippers
  • Contact lenses and glasses
  • Smartphones and chargers
  • Discharged (mother and child)

Never drink and smoke

Alcohol and tobacco are natural enemies of pregnant women.

For example, drinking alcohol during pregnancy increases the chance of suffering from Fetal Alcohol Syndrome.

Furthermore, there are all kinds of risks, such as being born underweight or with ADHD.

The same applies to tobacco.

Like drinking, it increases various risks such as premature birth, placental abnormalities, early water breakage, low birth weight and ectopic pregnancy.

To ensure a healthy baby and birth, it is absolutely essential not to drink or smoke during pregnancy.

Living away from crowds

Being in crowded places increases the risk of infections and other diseases, depending on the time of year.

During pregnancy, the mother’s health must be kept in good shape.

Therefore, avoid crowds with such risks as much as possible.

With regard to crowds, there is a high risk not only of infectious diseases, but also of second-hand smoke from cigarettes, as explained earlier.

To avoid unintentionally putting the foetus at risk, make sure you wash your hands, gargle and wear a mask when you go out.

What is the stable trimester of pregnancy? How to spend it and about NIPT【supervised by doctor】


This article explained when exactly the stable period of pregnancy starts and ends, and what to look out for during this period.

Once the pregnancy enters the stable period, the pregnant woman’s physical condition becomes more stable.

However, it is most important not to let your guard down and to spend time with your partner to reduce stress.

The postpartum period will be quite busy, so make sure you have done all the preparation you can during the stable period of pregnancy so that you can meet your baby in the best possible condition.

Article Editorial Supervisor

Dr. Kunihiko Shiraogawa

Dr. Kunihiko Shiraogawa

Head Doctor of Hiro Clinic NIPT Nagoya
Certified Obstetrician and Gynecologist, Japan Society of Obstetrics and Gynecology

As an obstetrician/gynecologist with nearly 40 years of extensive experience, he has worked with many pregnant women.
Currently, as the head doctor of Hiro Clinic NIPT Nagoya , he is in charge of NIPT testing, and also provides consultations to pregnant women online at all Hiro Clinic NIPT clinics in Japan.

Brief History

1982 – Aichi Medical University Hospital
1987 – OB/GYN, Kagoshima University Hospital
1993 – Head Doctor, Shiranogawa Clinic
2011 – Kaba Memorial Hospital
2019 – Okamoto Ishii Hospital
2020 – Head Director, Hiro Clinic NIPT Nagoya

Check his Profile here



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