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You already know that breast-feeding is one of the best things you can do for your baby, and although you’ve probably had to deal with engorgement, leaking breasts, and plugged milk ducts, there are certain things that can affect breast-feeding and even harm your baby. Here are seven:

1. Smoking
For most women who smoke, pregnancy is the incentive they need to quit. In fact, women who stopped smoking due to pregnancy continued to abstain from it 26 weeks after they gave birth, a 2010 study in the journal Nicotine and Tobacco Research found.

If you picked up the habit again after your pregnancy, it’s not only the toxins from the cigarettes that transfer into your breastmilk that are a problem, but the exposure alone is dangerous.

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Nevertheless, experts say that a diluted and small portion of nicotine passes through breastmilk. And although smoke exposure is a risk factor for Sudden Infant Death Syndrome (SIDS), breast-feeding is actually protective against SIDS, so women who smoke should breast-feed.

“Even though there may be something in the human milk that we would prefer the baby not have, there is so much the baby would get through the human milk that he would not get through formula that it would be far better for him to be breast-fed,” Diana West, an internationally board-certified lactation consultant and director of media relations for La Leche League in Chicago, Illinois, told Fox News.

Of course, you should never smoke near your baby — at home or in the car — but if you have to light up, put on an additional layer of clothing that can be removed later, and do so immediately after you breast-feed, when nicotine levels should be at their lowest until the next time you feed, Dr. Joan Meek, chair of the American Academy of Pediatrics’ section on breast-feeding and a professor of clinical sciences for the Florida State University College of Medicine, told Fox News.

Nearly all smoking cessation programs and products are OK to use while breast-feeding, but don’t also smoke while you’re using them because your baby could be exposed to toxic levels of nicotine.

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2. Bed-sharing
Whether you sleep with your baby in the same bed, or you often doze off while breast-feeding, bed-sharing can be dangerous.

About 3,500 infants die each year in the United States from sleep-related deaths, including sudden infant death syndrome (SIDS), ill-defined deaths, and accidental suffocation and strangulation, according to the American Academy of Pediatrics (AAP).

In 2016, the AAP released a policy statement on safe sleeping and acknowledged the importance of breast-feeding to prevent SIDS.

They also recommend babies share a bedroom with their parents until they turn 1 or at least for six months and say babies should be placed on their backs and on a separate sleep surface — in a bassinet, a crib or a co-sleeper, without sheets, blankets or pillows near the baby’s head or face.

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3. Mastitis
Breast-feeding moms have a higher incidence of mastitis, an inflammation of the breast that studies show affects about 10 percent of women.

You’re more likely to get mastitis if your breasts become full, if you have blocked milk ducts, or if you wear tight clothing or underwire bras. Mastitis doesn’t usually cause an infection of breast milk but of the tissues around the breasts.

Symptoms include redness, tenderness or firmness around the breast. You may also have a fever, fatigue and malaise.

Your doctor may prescribe antibiotics, but you should continue to breast-feed since emptying your breasts can resolve mastitis and your baby’s gastric juices kill the bacteria if you have an infection. Also, get plenty of rest and fluids to feel better fast.

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4. Alcohol
Alcohol is rapidly absorbed into the bloodstream, and although it quickly passes into breastmilk, it gets detoxified by the liver and is cleared out just as rapidly.

As a general rule, one drink — a 12-ounce beer, 4 ounces of wine, or 1 ounce of liquor —takes between two and three hours to metabolize, so feed your baby first and then have a drink. If you eat before having a drink, it will decrease and slow the absorption of the alcohol.

If you’re still feeling a buzz, the alcohol is still in your bloodstream and your breast milk, so you shouldn’t feed your baby. The practice of “pump and dump,” won’t get rid of the alcohol any faster, but you can pump for comfort or to keep up your milk supply.

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5. Marijuana
Although there is limited data on marijuana’s effects on babies, The American College of Obstetricians and Gynecologists (ACOG) and the American Academy of Pediatrics discourage moms from using it.

Like smoking, it’s the toxins and smoke exposure from marijuana that are dangerous, but the drug also accumulates in the baby’s fat cells. Because a mother under the influence is also likely impaired, it can affect her ability to care for her baby and increase the risk for SIDS, especially if she is bed-sharing.

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6. Prescription medications
Most prescription medications are safe to take while breast-feeding, but it’s always a good idea to speak to your provider before starting a new medication. You can also check the National Institutes of Health (NIH)’s LactMed® database for information about specific medications.

In general, medication passes into breast milk at 1 percent of the maternal dose, so the amount your baby receives is limited. Yet the safety of short-acting drugs are more predictable than long-acting drugs that are taken over a period of time because they can build up in your body. “The baby can’t metabolize medications as quickly as mom’s liver or kidney might,” Meek said.

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7. Vitamins and supplements
Most vitamins and supplements are safe to take while breast-feeding, but you should talk to your provider, especially if you’re taking any in high doses.

What’s more, herbal supplements in particular have variations in how they’re produced, and there is the potential for contamination and lack of quality control and some herbs like sage or peppermint can decrease breastmilk supply.