By Nicole Chavez CNN

(CNN) -- Millions of Americans are uncertain about their future as a new health care bill heads to the Senate.

The American Health Care Act would shake things up. It could open the door for insurers to charge sick people and pregnant women much higher premiums.

Under Obamacare, all insurers are required to charge everyone the same premium, despite their medical history. This new version of the bill would weaken protections for those with pre-existing conditions.

What is a pre-existing condition?

It's a "health problem you had before the date that new health coverage starts," the US Department of Health and Human Services says.

An estimated 52 million of adults under 65 years have pre-existing health issues, an analysis by the Kaiser Family Foundation found.

But the term itself is vague and every insurance company has their own lists of "declinable" or "uninsurable" conditions.

Some companies even considered domestic violence and rape a pre-existing condition before the Obamacare era.

Do I have a pre-existing condition?

Maybe. By law, there are not set parameters, and some insurers consider these as pre-existing conditions:

Acne
Anxiety
Asthma
Bipolar disease
Depression
Menstrual irregularities
Sex reassignment
Sleep apnea
Transsexualism

The list of pre-existing conditions could be endless. Three of the largest insurers in the US -- United Healthcare, Cigna and Anthem Blue Cross Blue Shield -- considered a person generally "uninsurable" and could decline coverage without reviewing any medical records if an applicant had a certain health issue. Insurance companies have listed the health issues but most reserved the right to add more conditions.

Here are the health issues they called pre-existing conditions prior to Obamacare. This list is not comprehensive.

AIDS or ARC
Acromegaly
Alzheimer's Disease
Amyotrophic Lateral Sclerosis
Anemia (Aplastic, Cooley's, Hemolytic, Mediterranean or Sickle Cell)
Aortic or Mitral Valve Stenosis
Arteriosclerosis
Arteritis
Asbestosis
Cancer
Cardiomyopathy
Cerebral Palsy (infantile)
Chronic Obstructive Pulmonary Disease
Cirrhosis of the Liver
Coagulation Defects
Congestive Heart Failure
Cystic Fibrosis
Demyelinating Disease
Dermatomyositis
Diabetes
Dialysis
Esophageal Varicosities
Friedreich's Ataxia
Hepatitis (Type B, C or Chronic)
Multiple Sclerosis
Muscular Dystrophy
Myasthenia Gravis
Obesity
Organ transplants
Paraplegia
Parkinson's Disease
Polycythemia Vera
Pregnancy
Psoriatic Arthritis
Pulmonary Fibrosis
Renal Failure
Sarcoidosis
Scleroderma
Sjogren's Syndrome
Tuberculosis

#IAmPreExistingCondition

Many have shared on Twitter their thoughts about the new health care bill and the potential impact on their own care, using the hashtag #IAmPreExistingCondition.

"I was diagnosed w Leukemia @ age 3 & have been in remission for 12 yrs but apparently I don't live the "right way" #IAmAPreexistingCondition," Eliana Espinosa wrote.

Espinosa is a student at St. Thomas University in Miami Gardens, Florida and visits an oncologist once a year for a checkup. But she's more concerned about her 57-year-old mother, who was diagnosed with Stage II breast cancer and gets treatment through the Affordable Care Act

Critics say women could be impacted by the list more than men as insurers could consider pregnancy, endometriosis, irregular periods and breast cancer as pre-existing conditions.

"Pregnancy is a preexisting condition under #trumpcare; but no worries, erectile dysfunction is still covered," wrote Kylie Chiyoko on Twitter.

An analysis of major health insurance companies' lists of pre-existing conditions did not reference erectile dysfunction, but that doesn't mean it wouldn't qualify as an uninsurable condition.

It's still unclear how quickly insurance premiums could rise. Under the new bill, states could apply for waivers to allow insurers to charge higher premiums based on medical history. States requesting waivers would have to set up programs -- such as high-risk pools -- to protect insurers from high-cost patients but no details on the process have been determined.

CNN's MJ Lee, Amanda Jackson, Christina Zdanowicz and Darran Simon contributed to this report.

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