Pregnancy week 18
Having gained approximately 20 pounds by the 18th week of pregnancy, it is now a little more likely that it will begin to show. Chances are that week 18 proves to be an uncomfortable time for laying down because of the expanding uterus. Furthermore, women should try to lay on their left side because this prevents the vena cava vein from being strained, which can slow the rate of blood flow to the heart and therefore make the heart work harder. Since the heart of the mother is already working about as half as much during pregnancy, the extra pressure is not a good idea. Pregnancy pillows can help ease the tension and help the mother rest and sleep much better. An ultrasound at this point should be able to determine the sex of the baby, however, it is important to keep in mind that ultrasounds are not completely efficient. The only fool proof method of determining a baby’s sex is by using the slightly dangerous procedure of amniocentesis. Waiting for delivery to find out the sex of the baby is sometimes preferred and often a nice surprise. Most home spun tactics of determining the baby’s sex are nothing more than guesses but can be a fun way for family members to bond with the baby. From this point on, the fetus is very sensitive to touch and sound.
At week 18 of pregnancy, the baby is about 6 inches in length and almost 5 ounces in weight. The fetus’s body is beginning to also develop a protective coating over the nerves referred to as Myelin. At this point, an ultrasound can also be used to determine any deformities within the heart of the baby. Knowing of the defects before delivery can prove to be essential in helping the baby survive post delivery. Ultrasounds can also be used to view the baby’s genitals at this point. The baby can even make facial expressions like yawning and frowning during this week. He can also grip the cord, flex muscles, and such his thumb.
Current guidance (today's medical sources): Week eighteen sees the baby's hearing develop, and it may begin to respond to sounds. The mid-pregnancy anatomy scan, which checks growth and development and may reveal the baby's sex if desired, often takes place around this time. Movements typically become clearer over the next few weeks.
Contact your healthcare provider promptly about heavy vaginal bleeding, severe or persistent abdominal pain, a high fever, severe or sudden headache, vision changes, or fainting. Seek urgent care if you are worried — these can be signs that need medical attention.
Sources: NHS — 18 weeks pregnant; ACOG — Ultrasound Exams; Mayo Clinic — Fetal development: The 2nd trimester. Informational only. See our sources & medical-review policy.
Frequently asked questions
How many months is 18 weeks pregnant?
Week 18 falls in the second trimester. Pregnancy is usually counted in weeks (about 40 in total) rather than months, because weeks are more precise.
What is happening to the baby at 18 weeks?
Hearing develops and the baby may respond to sounds; the digestive system is active.
What symptoms are common at week 18?
Movements may become clearer; the anatomy scan often happens around now. Symptoms vary a lot from person to person; discuss anything that worries you with your healthcare provider.
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See the week-by-week guide →Informational only — not medical advice. Pregnancy Week to Week is a general educational reference. It is not a substitute for professional medical care, diagnosis, or treatment. Every pregnancy is different: always consult your doctor, midwife, or other qualified healthcare provider about your own pregnancy, and never disregard or delay professional advice because of something you read here. In an emergency, contact your maternity unit or local emergency number immediately.