The second trimester starts with the 13th week of pregnancy and lasts up to the 28th week. It is often the most enjoyable phase of pregnancy, and is also referred to as the ‘honeymoon of pregnancy’. There is a general sense of well-being and all the sickness, nausea and other unpleasant symptoms of the first trimester disappear during this phase of pregnancy. The woman gains weight rapidly during the second trimester and experiences food cravings.
Hormonal changes during the second trimester of pregnancy
Hormonal levels continue to fluctuate during the second trimester of pregnancy. Due to this the expecting mother might experience mood swings and increased perspiration. There are chances of developing gestational diabetes during the second trimester. It will, however, disappear after delivery, but taking necessary care and precautions is essential.
A woman experiences following symptoms during the second trimester of pregnancy:
- Back pain – during pregnancy it is very normal to gain weight, and it can result in back pain. The top of the uterus can now be felt above the pubic bone.
- Increasing waistline – as the foetus is growing, the waistline increases considerably, and the baby bump starts to show.
- Nosebleeds and bleeding gums – increased blood circulation during the second trimester might cause nose bleeds and bleeding of gums.
- Heavy breathing – the pregnant woman may begin to take deeper breaths and experience shortness of breath during this period of pregnancy.
- Changes in nipples – as the breasts start preparing for lactation, the nipples become darker and the breasts may start secreting colostrum.
- Digestion problems – the digestive system slows down, and the lady may even experience heart burns, bloating and ingestion during the second trimester.
The placenta and umbilical cord
By the end of the first trimester the yolk completely shrivels, and now, as the second trimester commences, nutrition of and waste disposal from the foetus completely depends on the placenta and umbilical cord.
The umbilical cord connects the blood system of the foetus with the blood cells of the placenta, thus allowing the supply of nutrients and oxygen-rich blood through the umbilical vein, and disposing the waste and de-oxygenated blood via the umbilical arteries. The blood flow through the umbilical cord also plays a major role in regulating the temperature of the foetus.
The placenta acts as a barrier between the foetus and the external blood flow in the body of the expectant mother. It protects the foetus from waste, infections and bacteria as well as the variations of metabolism in the mother’s body. Placenta supplies the growing foetus with oxygen, and nutrients such as amino acids, minerals, glucose and aids removal of carbon dioxide. Placenta also secretes hormones like HCG, progesterone and oestrogen. These hormones are essential during pregnancy for maintaining the endometrial lining, without which there is a possibility of an abortion.
Changes during the second trimester of pregnancy- week by week
13th -14th week
In the 13th and 14th week of pregnancy, the foetus develops greater mobility. The baby discovers its mouth and starts sucking its thumb during the initial stages of the second trimester. The gut also develops and the baby can now swallow. Small amount of amniotic fluid may be ingested and then absorbed by the body. The kidneys also start functioning, as they cleanse the blood and pass the urine back into the amniotic fluids via the bladder and urethra. The nerve cells in the brain also grow and develop from the centre to the outer areas.
15th – 20th week
Between the 15th and the 20th week the foetus makes its presence felt. The mother can feel fluttering sensations, as the baby moves inside the womb. During this phase of the second trimester the reproductive system of the female foetus develops and the ovaries descend to the pelvis from the abdomen. Fingernails start growing and unique fingerprints are fully formed during this phase. The heart starts to pump faster, and it is also possible to listen to the baby’s heartbeats with foetal doppler. At this stage of pregnancy the weight of the foetus is approximately 300 to 400gm, and it measures around 6 inches. The foetus in 20 weeks is covered in fine hair called lanugo and a greasy coating called the vernix. This is a protective covering, protecting the foetus from its prolonged contact with amniotic fluids.
21st – 24th week
During the next 4 weeks of second trimester the movement of hands becomes more active and profound. The baby touches the face, body and the umbilical cord. The inner ear develops as well, and it is now mature enough to send signals to the brain. At this stage the bones contain bone marrow and produce red blood cells. Layers of fat also form under the skin and help in the development of the nervous system. Since most of the systems have developed and are functional, the foetus now stands a better chance of survival in case of a premature delivery. The breathing and reflex have developed, however, the respiratory system has not yet fully developed and the lungs are not ready for the outside world.
In the 25th week of the second trimester the baby starts responding to sounds and motion. The foetus responds to the noise outside the womb and reacts by moving hands and legs. The expectant mother can feel these movements in the form of kicks. The movement is generally a response to the outside noise, and it slows down as the noise subsides. During this phase of the second trimester of pregnancy the baby also develops balance mechanisms, and is now aware of any positional changes. By the end of the 25th week the foetus measures around 10 inches and weighs around 500gm.
26th – 28th week
During the last phase of the second trimester the foetus has grown to almost 13 inches and weighs about 850g, and the movements and structural development of the foetus can be assessed by a 4D ultrasound image. The initial eye colour of the foetus is blue, pigmentation and colour change occurs at birth. During the last phase of the second trimester the foetus also develops eyelashes and eyebrows, however, the eyes do not open as yet.
Care during the second trimester of pregnancy
- As the digestive system is weak even during the second trimester of pregnancy, the woman must eat nutritious and fibre-rich diet. Have small and frequent meals rather than three large meals.
- Continue the pre-natal medications and vitamins as per your doctor’s prescriptions.
- Avoid smoking, alcohol consumption or any other types of recreational drugs.
- It is time to avoid rigorous forms of exercise. Seek the help of your doctor or a specialised trainer who has good knowledge of the exercises that should be done during pregnancy.
- Get yourself checked for gestational diabetes.
- If you have gestational diabetes, take required care and maintain your diet regimen accordingly.
- Carrying or lifting heavy loads should be strictly avoided during this stage of pregnancy.