In pregnancy, you need to start some medications for both types of thyroid diseases, in consultation with your endocrinologist.
Treatment of hypothyroidism involves replacement with tyroid hormone i.e. T4. This hormone has been prepared with recombinant technology and is exactly same as is being produced inside your own thyroid gland.
For hyperthyroidism, drugs are given to suppress your thyroid gland from producing more thyroid hormone.

Maternal hypothyroidism poses a risk for both mother and baby, if left untreated. A pregnant woman’s thyroid hormones are vital not only for her but also for the development of her baby. Pregnant women with uncontrolled hypothyroidism can get high blood pressure, anemia (low red blood cell count), and muscle pain and weakness. There is also an increased risk of miscarriage, premature birth (before 37 weeks of pregnancy), or even stillbirth.

Pregnant women with uncontrolled hyperthyroidism may develop high blood pressure.

There is also an increased risk of miscarriage, premature birth, and having a baby with a low birth weight.

The possibility of the woman having a low birth weight baby and pre-term labor increases because of the poor sleep during this period. There is a link between birth complications and expectant mothers’ sleep that appears to be in disruptions to normal immune system function, caused by insufficient and low-quality sleep.

Several factors that contribute to the sleep difficulty during pregnancy are:
Hormonal changes. Pregnancy is a time of major hormonal shifts, which change sleep cycles and can disrupt sleep. Rising levels of progesterone may cause increase in BMR and may cause fatigue, as well as more sleepiness during the day, leaving women unusually wakeful at night. Fluctuating levels of estrogen also interfere with sleep. Levels of the hormone progesterone soar and your metabolism is running high. This can make you feel exhausted. At the same time, lower blood pressure and increased blood production might team up to sap your energy. If you have another child or children to care for, you might experience even more fatigue.

- Leg cramps: Dehydration, increase in weight and hormonal shifts all might cause the leg cramps and might hamper your sleep.

- Shortness of breath: Because of the increase in the uterus size that might put pressure on the diaphragm, which is one of the breathing muscle. This pressure increase in supine position while sleeping and worsens the ability to sleep.

- Nocturnal heartburn or gastro-esophageal reflux disease (GERD) : Pressure on the stomach by uterus and loosening of the lower esophageal sphincter leads to increased heartburn that again increases in lying down position.

- Pain Syndromes: Many types of pain that occur during this period like Back pain, Joint pain, Carpal tunnel syndrome (numbness in the hands that occurs due to fluid retention during this period) and Breast tenderness might hamper your sleep during this period. sleep.

- Itching: Pruritus during pregnancy might get exaggerated and lead to persistent itching that might increase your sleeplessness.

- Nightmares: Vivid dreams or nightmares increase during pregnancy because of the hormonal shifts that increase the REM Sleep during this period and it is responsible for increased dreaming, which might cause increased anxiety in the pregnant women

- Anxiety. Anxiety about the pregnancy itself as well as about managing all the aspects of their lives alongside the impending arrival of a new baby might scare away the women to make them sleepless.
It is also during this phase of pregnancy that preeclampsia may occur, which has an impact on the timing of sleep or circadian rhythm.