HOME  •  HEALTH  •  LIBRARY  •  AREAS  •  CENTERS  •  BOARDS  •  CHATS  •  JOIN FREE

MDAdvice.com Logo
   

Week 18
MDAdvice.com Home > Health Library > Your Pregnancy: Week by Week > Previous Week > Contents > Next Week

How Big Is Your Baby?

The crown-to-rump length of your growing baby is 5 to 5.6 inches (12.5 to 14cm) by this week. Weight of the fetus is about 5.25 ounces (150g).

How Big Are You?

Your uterus can be felt just below your bellybutton. If you put your fingers sideways and measure, it is about two finger widths below your bellybutton (about 1 inch below).

Your uterus is the size of a cantaloupe or a little larger. Your weight gain to this point should be 10 to 13 pounds (4.5 to 5.8kg). However, this can vary widely. If you have gained more weight than this, talk to your doctor. You may need to see a nutritionist. You still have more than half of your pregnancy ahead of you, and youÆre going to gain even more weight.

Gaining more than the recommended weight can make pregnancy and delivery harder on you. Extra pounds are hard to lose afterward.

Dieting during pregnancy is not a wise idea, but that doesnÆt mean you donÆt have to watch what you eat. You should! ItÆs important for your baby to get proper nutrition from the foods you eat. Choose food for the nutrition it provides you and your growing baby.

How Your Baby Is Growing and Developing

Your baby is continuing to grow and to develop, but now the very rapid growth rate slows down a little. As you can see in the illustration on page 154, your baby has a very human appearance now.

Development of the Heart and Circulatory System

At about the third week of fetal development, two tubes join to form the heart. The heart begins to contract by day 22 of development or about the beginning of the 5th week of gestation. A beating heart can be seen as early as 5 to 6 weeks of pregnancy during an ultrasound examination.

The heart tube divides into bulges. These bulges develop into heart chambers, called ventricles (left and right) and atria (left atrium and right atrium). These divisions occur between weeks 6 and 7. During week 7, tissue separating the left and right atria grows and an opening between the atria called the foramen ovale appears. This opening lets blood pass from one atrium to the other, allowing it to bypass the lungs. At birth, the opening closes.

The ventricles, the lower chambers of the heart (lying below the atria), also develop a partition. The ventricle walls are very muscular. Blood is pumped from the left ventricle to the body and brain, and from the right ventricle to the lungs.

Heart valves develop at the same time as the chambers. These valves fill and empty the heart. Heart sounds and heart murmurs are caused by blood passing through these valves.

Your baby gets oxygen from you. Blood from your baby flows to the placenta through the umbilical cord. In the placenta,

oxygen and nutrients are transported from your blood to the fetal blood. Although the circulation of your blood and that of your baby come close, there is no direct connection. These circulation systems are completely separate.

Your baby continues to grow. By this week, it is about 5 inches (12.5cm) from crown to rump. It looks much more human now.

At birth, the baby has to go very rapidly from depending entirely on you for oxygen to depending on its own heart and lungs. The foramen ovale closes, and blood goes to the right ventricle, the right atrium and to the lungs for oxygenation for the first time. It is truly a miraculous conversion.

At 18 weeks of gestation, ultrasound can detect some abnormalities of the heart. This can be helpful in identifying problems such as Down syndrome. A skilled ultrasonographer looks for specific heart defects. If an abnormality is suspected, further ultrasound exams may be ordered to follow a babyÆs development as pregnancy progresses.

Changes in You

Does Your Back Ache?

Nearly every pregnant woman experiences backache at some time in pregnancy. It may have occurred already, or it may come later as you get bigger. Some women have severe back pain following excessive exercise, walking, bending, lifting or standing. It is more common to have mild backache than severe problems. Some women need to take special care getting out of bed or getting up from sitting. In severe instances, some women find it difficult to walk.

A change in joint mobility may contribute to the change in your posture and may cause discomfort in the lower back. This is particularly true in the latter part of pregnancy.

The growth of the uterus moves your center of gravity forward, over your legs. Your joints are looser, and the joints around the pelvis can be affected. Changes are believed to be caused by hormonal increases.

Tina came to the office after a long day at the grocery store, where she was a clerk. She told me her back ached a lot, and she wanted to know what to do. I told her that backache can often be helped with heat, rest and analgesics, such as acetaminophen (Tylenol). Special maternity girdles are available that can provide some support. Keeping weight under control and exercising may also help. In a severe case, physical therapy or a consultation with an orthopedic surgeon might be necessary.

Watch your diet and weight gain. Continue exercising within guidelines during pregnancy. Get in the habit of lying on your side when you sleep. Find time to get off your feet and lie down for 30 minutes on your side. If you have other children, find ways to get some rest during the day. If they take a nap, get some rest of your own. Start early to do these things; itÆll pay off as your pregnancy progresses.

Nasal Problems
Some women complain of stuffiness in their nose or frequent nosebleeds during pregnancy. Some researchers believe these symptoms occur because of changes in circulation due to hormonal changes during pregnancy. This can cause the mucous membranes of your nose and nasal passageways to swell and to bleed more easily.

DonÆt try different medications to help, such as decongestants or nasal sprays. Many of these are combinations of several medications and may be ill-advised during pregnancy.

It may help to use a humidifier, particularly during the winter months when heating may dry out the air. Some women get relief from increasing their fluid intake and using a gentle lubricant, such as petroleum jelly. As for other relief, you may have to wait until your baby is born to breathe normally through your nose again.

How Your Actions Affect Your BabyÆs Development

Some women are very involved in fitness activities. They want to know what they can do and what to avoid while pregnant.

Pregnant women can participate safely in many sports and other activities. This is a very different attitude from the ones 20, 30 and 40 years ago. Bed rest and decreased activity were common then. Today, we believe exercise and activity can benefit you and your growing baby.

As with any activity, discuss your particular activities with your doctor. If you are a high-risk patient or have had several miscarriages, itÆs particularly important to discuss exercise with your doctor before starting an activity. Now is not the time to train for any sport or to increase activity.

What about specific sports? Below is a discussion of various activities you might be interested in. (Aerobic exercise is discussed in Week 3.)

Swimming

Swimming can be very good for you when youÆre pregnant. It may also make you feel comfortable. The support and buoyancy of the water can be relaxing.

If you swim, you are encouraged to swim throughout pregnancy. If you canÆt swim, exercising in a swimming pool in the shallow end can be very enjoyable. Classes are offered in many places. Ask at local spas or health clubs.

Bicycling

Now is not the time to learn to ride a bike. If youÆre comfortable riding and have safe places to ride, it can be an exercise you can enjoy with your partner or family.

Your balance will change as your body changes. This can make getting on and off a bicycle difficult. And a fall from a bicycle could injure you or possibly injure your baby.

A stationary bicycle is good for bad weather and for later in pregnancy. Many doctors suggest you ride a stationary bike to avoid the danger of a fall in the last 2 to 3 months of pregnancy.

Walking

Walking is a very desirable exercise during pregnancy. If you are just starting, gradually increase the time and distance you walk. Two miles of walking at a good pace is adequate.

Walking can be a good time for you and your partner to talk. Even when the weather is bad, you can walk in places such as enclosed shopping malls to get a good workout. As pregnancy progresses, you may need to decrease your speed and distance.

Jogging

Many women continue to jog during pregnancy. Jogging may be permitted during pregnancy, but check with your doctor first. If you are a high-risk pregnancy, jogging is not a good idea.

Pregnancy is not the time to increase mileage or to train for a race. Wear comfortable clothing and shoes with good cushioning. Allow plenty of time to cool down.

During the course of your pregnancy, youÆll probably need to slow down and to decrease the number of miles you run. You may even change to walking. If you notice pain, contractions, bleeding or other symptoms during or after jogging, call your doctor immediately.

Other Sports Activities

Tennis and golf are safe but may provide little actual exercise. Horseback riding is not advisable during pregnancy. Avoid water skiing while youÆre pregnant. Bowling is OK, although the amount of exercise you get varies. Be careful in late pregnancy; back strain could occur. Your balance changes, which could make bowling difficult for you.

Talk to your doctor about snow skiing before you hit the slopes. Again, in the latter part of pregnancy, your balance changes significantly. A fall could be harmful to you and your baby. Most physicians agree that skiing in the second half of pregnancy is not a good idea. Some doctors may allow skiing in early pregnancy, but only if there are no complications with this or previous pregnancies.

Riding snowmobiles and motorcycles is not advised. Some doctors may allow you to ride if it is not strenuous. However, most believe the risk is too great, especially if you have had problems during this or other pregnancies.

Tip for Week 18
During exercise, your oxygen demands increase. Your body is heavier, and your balance may change. You may also tire more easily. Keep these points in mind as you adjust your fitness program.

You Should also Know

Bladder Infections

One of the first symptoms you may notice early in pregnancy is frequent urination. This will continue during pregnancy and may get you up frequently at night.

It is more common to get urinary-tract infections during pregnancy. Other names for urinary-tract infections are bladder infections and cystitis. Symptoms of a bladder infection include painful urination, particularly at the end of urination, the feeling of urgency to urinate and frequent urination.

Most doctors will test your urine at your first visit. Your doctor will check it at other times during pregnancy and for infection if and when bothersome symptoms arise.

You can help avoid infection by not ôholdingö your urine. Empty your bladder as soon as you feel the need to. Drink plenty of fluid; cranberry juice may help avoid infections. For some women, it helps to empty the bladder after having intercourse.

See your doctor if you think you have a bladder infection. It should be treated. Some antibiotics are safe to use during pregnancy for this problem.

If left untreated, urinary-tract infections can get worse. They can even lead to pyelonephritis, a serious kidney infection. If you have pyelonephritis, you may have to be hospitalized to treat the infection.

A urinary-tract infection during pregnancy may also be a possible cause of premature labor or a low-birth-weight infant. If you think you have an infection, talk to your doctor. If you are diagnosed as having a urinary-tract infection, take the full course of antibiotics prescribed by your doctor.

Previous Week > Contents > Next Week

 

Send This Article to a Friend Return to Health Library Main Page
From Your Pregnancy Week by Week by Glade B. Curtis, M.D., OB/GYN. Copyright by Fisher Books. Electronic rights by Medical Data Exchange.

 

 Home  |  Help  |  Feedback  |  Privacy Policy  |  Register  |  Contact Us  |  Visitor Survey  |  Subscribe to HealthMail  |  Advertising  |  About MDAdvice.com

Copyright © The Online Medical Network Inc. All rights reserved. All material provided by MDAdvice.com is intended for informative purposes only and is not a substitute for professional medical advice. Please consult your physician with any questions or concerns you may have regarding your health. Use of this site indicates your agreement with the Terms of Use.