Ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), was FDA-approved for prescription use in 1974 and introduced to the market as an over-the-counter analgesic 10 years later. It has been popular ever since, and today over 20 million prescriptions for the drug are filed in the US alone every year.  In a prescription context, ibuprofen may be used to make the lives of people with osteoarthritis, rheumatoid arthritis, swelling, stiffness, and even menstrual pains more comfortable. As an over-the-counter drug, you may choose to use ibuprofen for aches, pains, and fevers.  When you choose ibuprofen, you may find the fact that it reduces inflammation in addition to relieving pain quite appealing.
All medications carry risks and can come with side effects, while no medication is the right choice for everyone. It is especially important to make sure that you choose the safest possible medication for you while you are pregnant, since some drugs are linked to an increased risk of miscarriage while others have the potential to cause birth defects. During pregnancy, you're also especially likely to encounter the kinds of aches and pains that would lead you to pop an OTC painkiller if you weren't expecting.
Ibuprofen: Not As Safe As You May Think?
All medications come with long, scary lists of potential adverse affects, one of which is quite likely to include something along the lines of "may cause death". Ibuprofen is no exception, but should that scare you? The answer is yes — certainly enough to carefully consider the use of the popular analgesic, especially if you take it often, whether you are pregnant or not.
Before using ibuprofen, you're advised to:
- Let your doctor know if you're allergic to ibuprofen or any other NSAID — this one pretty much falls into the "stating the obvious" category!
- Tell your doctor about any and all other medications and nutritional supplements that you are taking. Also, don't take ibuprofen with other painkillers unless your doctor tells you to.
- Let your doctor know if you have suffered a heart attack or stroke or have a family history of these, if you smoke, if you're asthmatic, or if you have or have had hypertension, diabetes, or high cholesterol, or if you have phenylketonuria.
- If you're pregnant, trying to conceive, or breastfeeding. According to the US National Library of Medicine, "if you become pregnant while taking ibuprofen, call your doctor". 
Having said that, many people can take ibuprofen once in a blue moon quite safely. What does science have to say about the specific risks of using ibuprofen during pregnancy, though?
Can You Safely Take Ibuprofen During Pregnancy?
While many expectant mothers have taken ibuprofen during pregnancy without suffering any adverse effects, just like they will probably continue to do in the future, the short answer is "no". You should be very careful before using ibuprofen during pregnancy.
One 2003 study came to the conclusion that NSAIDs beside Aspirin increase a pregnant woman's risk of miscarriage by as much as 80 percent, and that using an NSAID such as ibuprofen is particularly risky around the very time of conception . Some studies did not find an association between NSAID use during pregnancy and birth defects , while other research notes that there does appear to be an increase in certain specific birth defects in mothers who use NSAIDs, including ibuprofen, during pregnancy. These birth defects are, the authors say, "some neural tube defect groups, anophthalmia/microphthalmia, pulmonary valve stenosis, amniotic bands/limb body wall defects, and transverse limb deficiencies".  Later in pregnancy, NSAID use may also reduce your levels of amniotic fluid to dangerous levels .
Overall, research on the safety of the use of ibuprofen during pregnancy makes a strong enough case against for national bodies such as the British National Health Service to advise pregnant women against women against taking the painkiller while expecting. 
In short, it's best to stay away from ibuprofen during your pregnancy.
If I Can't Use Ibuprofen During Pregnancy, What Else Should I Take?
While Aspirin, another NSAID, is also but less strongly associated with miscarriage, low-dose aspirin during pregnancy is sometimes recommended to expectant mothers who have suffered recurrent miscarriages. In this case, it is being taken specifically to reduce the risk of blood clots within the placenta, rather than as a painkiller and fever reducer.