Most women in developed countries get through pregnancy and birth without serious problems.

But several adverse conditions –  including miscarriage, gestational diabetes, and preeclampsia – are all too common.

A new animal study from Australia suggests that fish oil supplements may help deter these three conditions, each of which has been linked to inflammation in the placenta.

How do doctors define miscarriage, gestational diabetes, and preeclampsia?
  • Miscarriage means pregnancy loss from natural causes before 20 weeks. Up to 20 percent of pregnancies end in miscarriage, often before a woman knows she's pregnant.
  • Gestational diabetes means high blood glucose (sugar) levels in a pregnant woman who's never had diabetes. It affects 18 percent of pregnancies.
  • Preeclampsia (pree-eh-clamp-see-ah) is a potentially dangerous condition that affects up to eight percent of first-time mothers in the U.S. 
Symptoms of preeclampsia typically appear in middle to late pregnancy and include an abrupt rise in blood pressure, leaking of protein into urine, headaches, and swelling of the hands, feet, and face. (For more information, visit the Preeclampsia Foundation.)

In 2007, a University of Pittsburgh analysis linked low vitamin D levels to a five-fold increase in risk of preeclampsia … see “Pregnancy Danger Linked to Low Vitamin D Levels”.

Then, in 2009, separate studies from Norway and Seattle linked low vitamin D and omega-3 blood levels to a higher risk of preeclampsia … see “Pregnancy Danger May be Deterred by Vitamin D and Omega-3s”.

Inflammation, pregnancy problems, and omega-3s
Inflammation of the placenta occurs in pregnancy disorders, including gestational diabetes, preeclampsia, and miscarriage, and is believed to promote and exacerbate these disorders.

Recent research revealed that when people consume the two major omega-3s found in fish or fish oil – called DHA and EPA – the body converts them into potent anti-inflammatory compounds called resolvins and protectins. 

Omega-3-derived resolvins and protectins stop the inappropriate, damaging inflammation underlying major degenerative conditions such as cardiovascular disease … and may help ease pain (see "Omega-3 DHA Derivative May Replace Opiates").

Importantly, clinical research shows that people who take supplemental fish oil produce resolvins and protectins at levels that exert substantial anti-inflammatory and inflammation-resolving effects (Mas E et al. 2012).

Mother's milk found high in omega-3-derived resolvins
The omega-3 fatty acids found in human cells and in fish oil – DHA and EPA – are essential to fetal brain and eye development.

Of the two omega-3s, DHA is the most important to get from your diet, because our bodies can make ample EPA from DHA.

The human body can make DHA from the plant-source omega-3 called ALA … but only one to 10 percent of dietary ALA gets converted to DHA (see our “Omega-3 Facts & Sources” page).

The fatty acid mixture of human milk is ideal for newborns … but surprisingly little has been known about its composition in the first few weeks of nursing.

Earlier this year, Swiss researchers analyzed the composition of 94 human milk samples from 30 mothers, collected over the first month of lactation (Weiss GA et al. 2013).

Over the first four weeks of nursing, levels of DHA – the omega-3 essential to brain and eye development – in the nursing mothers' milk dropped.

That drop in the DHA levels of maternal milk was expected, because mothers transmit much of their own DHA to the fetus and nursing newborn, and quickly drain the available supply.

But they found that levels of omega-3-derived resolvins rose in the mothers' milk over the same period.

As the Swiss doctors said, “… the high content of anti-inflammatory and pro-resolving lipid mediators [DHA-derived resolvins] … may indicate their role in neonatal immunity and may be one of the reasons for the advantage of human milk over infant formula.” (Weiss GA et al. 2013)

Recent studies laid a foundation for the new research
An Australian lab study published earlier this year showed that supplemental omega-3 fish oil reduced oxidative stress – a major cause of inflammation – in pregnant rodents' placentas, while boosting fetal and placental weight beneficially (Jones ML et al. February 2013).

The Aussie team make a key point: “Our data indicate that [omega-3 fish oil] supplementation reduces placental oxidative stress and enhances placental and fetal growth.” (Jones ML et al. February 2013)

The results of that rodent study supported the idea that fish and fish oil might reduce the risk or severity of inflammation-related complications of pregnancy.

Now, the same Australian team reports that fish oil reduced inflammation in the placenta and fetuses of pregnant rats … and the fish oil did that by raising the levels of DHA-derived resolvins in these critical places.

New study sees fishy omega-3s as possible pregnancy aids 
For their new study, researchers from The University of Western Australia (UWA) added fish oil to the diets of pregnant rats (Jones ML et al. 2013).

After being fed fish oil, the animals' placentas had substantially higher levels of DHA-derived anti-inflammatory resolvins and protectins in their placentas and fetuses.

The outcomes of the UWA study shows the omega-3 fatty acids present in fish oil yielded potent compounds that helped limit and end inflammation in the their placentas.

Judging by these results, women who take fish oil during pregnancy might limit the risk and effects of gestational diabetes, preeclampsia, miscarriage, and other complications.

Doctoral candidate and lead researcher Megan Jones believes that their results suggest that fish-source omega-3s may also improve the health and functioning of the placenta:
“The omega-3 fatty acids in fish oil are known to limit inflammation, and … they do this by being converted to resolvins that reduce inflammation after it's occurred. These findings significantly help further our understanding of how fish oil intake may be beneficial during pregnancy.” (UWA 2013)

Of course, clinical trials will be needed to confirm these findings in women, and further explore the beneficial potential of supplemental fish oil to pregnant mothers and their fetuses.

  • Jones ML, Mark PJ, Keelan JA, Barden A, Mas E, Mori TA, Waddell BJ. Maternal dietary omega-3 fatty acid intake increases resolvin and protectin levels in the rat placenta. J Lipid Res. 2013 Aug;54(8):2247-54. doi: 10.1194/jlr.M039842. Epub 2013 May 30.
  • Jones ML, Mark PJ, Mori TA, Keelan JA, Waddell BJ. Maternal dietary omega-3 fatty acid supplementation reduces placental oxidative stress and increases fetal and placental growth in the rat. Biol Reprod. 2013 Feb 14;88(2):37. doi: 10.1095/biolreprod.112.103754. Print 2013 Feb.
  • Mas E, Croft KD, Zahra P, Barden A, Mori TA. Resolvins D1, D2, and other mediators of self-limited resolution of inflammation in human blood following n-3 fatty acid supplementation. Clin Chem. 2012 Oct;58(10):1476-84. Epub 2012 Aug 21.
  • University of Western Australia (UWA). Fish oil found to help serious pregnancy complications. July 29, 2013. Accessed at 
  • Weiss GA, Troxler H, Klinke G, Rogler D, Braegger C, Hersberger M. High levels of anti-inflammatory and pro-resolving lipid mediators lipoxins and resolvins and declining docosahexaenoic acid levels in human milk during the first month of lactation. Lipids Health Dis. 2013 Jun 15;12:89. doi: 10.1186/1476-511X-12-89.