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PAPERS: Sjúrdur Fródi Olsen and Niels Jørgen Secher Low consumption of seafood in early pregnancy as a risk factor for preterm delivery: prospective cohort study BMJ 2002; 324: 447-450 [Abstract] [Full text]

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long chain polyunsaturated fatty acids and fetal programming

Undurti N Das   (23 February 2002)

The advantage of having Seafood in our meal?

Abdul Karim J Al-Sheikhli   (26 February 2002)

Fish for pregnancy

Mohammad G. Saklayen   (26 February 2002)

Does low intake of n-3 polyunsaturated fatty acids negatively affect uteroplacental circulation?

Michael Syndos, Narendra Pisal, Research Fellow and Theresa Freeman Wang, Specialist Registrar   (27 February 2002)

Now all we need is a mechanism and a hypothesis to test.

Peter R Reynolds   (27 February 2002)

Fish OIl Supplementation and Duration of Labour

Shawn C. Gallagher   (27 February 2002)

Is it really due to sea food?

Valmiki Kolmi Nagaraj, Anandhi Nagaraj   (27 February 2002)

Antenatal care and sea fish

Michel R Odent, Paul A De Reu and Suzanne Colson   (11 March 2002)

The safety of eating fish during pregnancy needs to be determined

Roger A Harrison, Lee Hooper   (12 March 2002)

Those do not eat sea food also selective in other dishes

Clayman ZK Zhang   (26 April 2002)

long chain polyunsaturated fatty acids and fetal programming 23 February 2002
Undurti N Das, Research Director & Chairman EFA Sciences LLC, 1420 Providence Highway, Suite # 266, Norwood, MA 02062, USA Send response to journal: Re: long chain polyunsaturated fatty acids and fetal programming	Fetal growth retardation is associated with adverse health oucomes in adulthood, including abnormal lipid values, diabetes mellitus, hypertension, and death from coronary heart disease. One characteristic feature of these diseases is the near universal presence of insulin resistance and hyperinsulinemia. Low-grade systemic inflammation is present in these diseases as evidence by the occurrence of high plasma levels of C-reactive protein, interleukin-6, and tumor necrosis factor- alpha. In this context, it is interesting to note that n-3 fatty acids are useful in the treatment of hyperlipidemias, enhance insulin sensitivity, lower blood pressure, and prevent coronary atherosclerosis. N-3 fatty acids also inhibit the production of interleukin-6 and tumor necrosis factor-alpha and thus, show anti-inflammatory actions. In patients with diabetes mellitus, hypertension, and coronary heart disease the plasma levels of eicosapentaenoic acid, docosahexaenoic acid and n-6 arachidonic acid concentrations are low. These evidence coupled with the observation that n-3 fatty acids increase birth weight and fetal growth rate suggests that these fatty acids if provided in adequate amounts from fetal life to early chidhood may actually program the fetus not to develop these adult diseases. This may also explain why breast fed subjects have lower incidence of these diseases since breast milk is rich in these long chain fatty acids. In view of this, I suggest that providing adequate amounts of both n-3 fatty acids and arachidonic acid during the perinatal period will ensure the prevention of metabolic syndrome X and its associated diseases.
The advantage of having Seafood in our meal? 26 February 2002
Abdul Karim J Al-Sheikhli, Loc,Consultant Psychiatrist Medical Center,2manor Court Avenue,Nuneaten CV11 5HX,England Send response to journal: Re: The advantage of having Seafood in our meal?	Dear Sir, It was very interesting to read the paper of Sjurdur Frodi Olsen & Niels Jorgen Secher(1),Low consumption of Seafood in early pregnancy as a risk factor for preterm delivery,Prospective Study. It is interesting that many papers in the past show the usefulness of Seafood consumption on our physical and psychological wellbeing, eating fish is protective for Cardiovascular function ,especially for those at risk of coronary arterial disease(2), Intake of fish & omega -3 polysaturated fatty acids is associated with a reduced risk of thrombotic infarction in women...etc(3), Rheumatoid Arthritis patients benefit from diet rich in fish, a conclusion from a study from Klaksvik (4),and its good effect on mood, low depressive episodes and rates of suicides in areas of high consumption of fish(5),and lack of seasonal mood changes in high consumption of fish areas as in Iceland(6). Ref, 1.Sjurdur Frodi Olsen&Niels Jorgen Secher , Low Consumption of Seafood in early pregnancy as a risk factor for preterm delivery,Prospective study,BMJ,2002,324:447-450. 2.Nestel P,Effect of fish oil and fish on cardiovascular diseaes,Curr Atheroscler Res,2001 Jan,3(1):68-73,Review. 3.Iso H,Rexrode KM,Stampfer MJ etal,Intake of Fish and Omega-3fatty acids and risk of stroke in women,Jama,2001 jan 17,285(3):304-12. 4.Recht L,Helin P,Rasmussen JO etal ,J.Int.Med ,1999 Jan,227(1):149-55. 5.Tanskanen A,Hibbeln JR,Hinntikka J, etal,Fish consumption ,depression ,& suicidality in a general population, Arch G Psychiatry,2001 May,58(5):512-3. 6.Cott J,Hibbeln JR,Lack of Seasonal mood changes in Icelanders,Am J Psychiatry,2001 Feb,158(2):328.
Fish for pregnancy 26 February 2002
Mohammad G. Saklayen, Professor of Medicine Wright State University, Dayton OH 45428 Send response to journal: Re: Fish for pregnancy	While many customs in many cultures defy any scientific explanation, there comes times when new studies shed light on some hitherto unexplained customary practices. The study by Olsen et al reminds me that in Bengal ( Bangladesh and West Bengal state of India ) it is customary to feed the pregnant woman a good serving of fish including the head of the fish (along with the fish brain with its high fat content) during the ceremonial baby shower. While one meal of fish may not be good enough to prevent intrauterine growth retardation and preterm delivery, the idea behind the custom seems to be the promotion of fish consumption during pregnancy. I wonder if any other societies have similar customs .
Does low intake of n-3 polyunsaturated fatty acids negatively affect uteroplacental circulation? 27 February 2002
Michael Syndos, Research Fellow Dept of Women and Children's Health, The Whittington Hospital, London, N19 5NF, Narendra Pisal, Research Fellow and Theresa Freeman Wang, Specialist Registrar Send response to journal: Re: Does low intake of n-3 polyunsaturated fatty acids negatively affect uteroplacental circulation?	Dear Editor, Olsen and Secher report that low consumption of fish is a strong risk factor for preterm delivery and low birth weight and that the associations were strongest below a daily intake of 0.15g long chain n-3 polyunsaturated fatty acids(PUFAs) or 15g fish1. In 1986 Olsen and al had reported that intake of marine fat rich in n-3 PUFAs may increase birthweight by prolonging gestation2. The beneficial effect of n-3 PUFAs in the human cardiovascular system is proven3. Longchain n-3 PUFAs influence vascular function positively by several different cellular control mechanisms. These include interactions between platelets and the vascular wall, alterations on haemostatic function and lipoprotein metabolism, inhibition of proliferation of smooth muscle cells at the gene expression level and therefore growth of the atherosclerotic plaque. They also influence vascular reactivity, change vascular tone via actions on selective ion channels, maintain vascular integrity and modify expression of inflammatory cytokinesis and adhesion molecules. Intake of fish oil reduces blood pressure and modifies vascular neuroeffector mechanisms4. Interestingly, increased resistance and reduced blood flow in the uteroplacental circulation during pregnancy, are strongly associated with low birth weight, preterm delivery, and pre-eclampsia5. So, it is possible that the observation of Olsen and Secher can be explained by the lack of n-3 PUFAs action on the endothelial cells of the uteroplacental circulatory vessels. We believe that further research on the effect of n-3 PUFAs on cellular control mechanisms and the final histological and physiological changes that they produce to the vessels participating in uteroplacental circulation is needed. References 1. Olsen SF, Secher NJ. Low consumption of seafood in early pregnancy as a risk factor for preterm delivery: prospective cohort study. BMJ 2002;324:447-451 2. Olsen SF, Hansen HS, Sorensen TI, Jensen B, Secher NJ, Sommer S, et al Intake of marine fat, rich in ( n-3)- polyunsaturated fatty acids, may increase birthweight by prolonging gestation. Lancet 1986; 2: 367-369 3. Nordoy A, Marchioli R, Arnesen H, Videbaeck J. n-3 polyunsaturated fatty acids and cardiovascular diseases. Lipides 2001; 36 Suppl: S127-9 4. Abeywardena MY, Head RJ. Longchain n-3 polyunsaturated fatty acids and blood vessel function. Cardiovasc Res 2001 Dec; 52 :361-371 5. Harrington K, Carpender RG, Goldfrad C, Campell S. Transvaginal Doppler ultrasound of the uteroplacental circulation in the early prediction of pre-eclampsia and intrauterine growth retardation. Br J Obstet Gynaecol 1997; 104: 674-81
Now all we need is a mechanism and a hypothesis to test. 27 February 2002
Peter R Reynolds, British Heart Foundation Research Training Fellow Departments of Paediatrics and Immunology, Imperial College, Hammersmith Hospital, London W12 0NN Send response to journal: Re: Now all we need is a mechanism and a hypothesis to test.	Dear Sir Olsen and Secher’s paper shows that a small regular consumption of fish before 16 weeks gestation may reduce the risk of subsequent preterm delivery and low birth weight. Disappointingly however the authors did not stratify the outcome data, nor did they discuss plausible biological mechanisms to explain the observed effects. The causes of prematurity are heterogenous, particularly when a definition of less than 37 weeks is used. A useful, albeit arbitrary, subset, particularly when considering an inflammatory aetiology, is to restrict analysis to those delivered at less than 30 weeks gestation. We know that preterm delivery before 30 weeks is strongly related to the presence of inflammation, with more than 50% of delivered fetuses having evidence of chronic chorioamnionitis (1, 2). There is also strong evidence that brain injury (3) and chronic lung disease (4, 5) in premature infants is also related to intrauterine inflammation. A significant body of epidemiological (6) and in-vitro data suggests that the PUFAs, particularly the omega-3 type, can modulate inflammation. Cultured endothelial cells preincubated with PUFAs demonstrated reduced expression of leukocyte adhesion molecules such as VCAM-1, ICAM-1 and E- selectin (7). In a study comparing populations with high and low dietary intake of omega-3 PUFAs, the greatest reduction of fatty streaks occurred in the youngest, high intake groups (8). This suggests that the early inflammatory changes at the endothelium can be modified by consumption of omega-3 PUFAs, which is clearly a transferable hypothesis. If the anti-inflammatory effects of PUFAs are indeed the “hidden” message in this paper, then presenting the outcome data for prematurity less than 30 weeks might go some way towards testing the hypothesis that omega-3 PUFAs reduce preterm deliveries <30 weeks by reducing inflammation. A second point is that the authors might have more usefully presented their data as the numbers needed to treat (NNT) for the different groups. For the minimum fish intake group (QUANT1) the data gives an NNT of 33 (95%CI 15-392) for preterm delivery (<37 weeks) and an NNT of 25 (13- 75) for low birth weight. For the QUANT5 group the NNTs are 24 (13-65) and 20 (12-41) respectively. These look encouraging - but if the hypothesis for the biological mechanism is correct, then the numbers for preterm delivery <30 weeks might be striking. Of course it would be a seductively simple manoeuvre to incorporate this dietary advice in pre- and early pregnancy counselling, particularly to those with a previous history of LBW/preterm delivery. However the data presented fails to convince that we should be advising dietary changes especially as a previous study in the same population found no association between fish intake and preterm delivery (9). Clearly further research into the effects of PUFAs on the low-grade chronic inflammation implicated in LBW/prematurity (as well in other diseases) is urgently required. I would also urge the authors to present the data adjusted for deliveries less than 30 weeks. Yours sincerely Dr Peter Reynolds References: (1) Goldenberg RL, Hauth JC, Andrews WW: Intrauterine infection and preterm delivery. N Engl J Med 2000, 342:1500–1507. (2) Dammann O, Leviton A. Maternal intrauterine infection, cytokines, and brain damage in the preterm newborn. Pediatr Res. 1997 Jul;42(1):1-8. (3) Duggan PJ, Maalouf EF, Watts TL, Sullivan MH, Counsell SJ, Allsop J, Al-Nakib L, Rutherford MA, Battin M, Roberts I, Edwards AD. Intrauterine T-cell activation and increased proinflammatory cytokine concentrations in preterm infants with cerebral lesions. Lancet. 2001 Nov 17;358(9294):1699-700. (4) Yoon BH, Romero R, Kim KS, Park JS, Ki SH, Kim BI, Jun JK: A systemic fetal inflammatory response and the development of bronchopulmonary dysplasia. Am J Obstet Gynecol 1999, 181:773–779. (5) Watterberg KL, Demers LM, Scott SM, Murphy S: Chorio-amnionitis and early lung inflammation in infants in whombronchopulmonary dysplasia develops. Pediatrics 1996, 97:210–215. (6) Leaf A, Weber PC. Cardiovascular effects of n-3 fatty acids. N Engl J Med 1988 Mar 3;318(9):549-57 (7) De Caterina R, Liao JK, Libby P. Fatty acid modulation of endothelial activation. Am J Clin Nutr. 2000 Jan;71(1 Suppl):213S-23S. (8) Newman WP, Middaugh JP, Propst MT, Rogers DR. Atherosclerosis in Alaska natives and non-natives. Lancet 1993;341:1056–7. (9) Kesmodel U, olsen SF, Salvig JD. Marine n-3 fatty acid and calcium intake in relation to pregnancy induced hypertension, intrauterine growth retardation and preterm delivery: a case-control study. Acta Obstet Gynecol Scand 1997;76:38-44
Fish OIl Supplementation and Duration of Labour 27 February 2002
Shawn C. Gallagher, Registered Midwife 23 Stonegate Road, Toronto, ON Canada M8Y 1V7 Send response to journal: Re: Fish OIl Supplementation and Duration of Labour	I note with excitment new research from Olsen and Secher. I am a Registered Midwife and have been recommending essential fatty acid intake to pregnant and lactating women for years now. There is a large body of research to support the prenatal intake of omega 3 oils for the health of the developing brain and eyes of the fetus. Research on the use of Omega 3 oils and mood disorders suggest that intake in pregnancy and postpartum may be protective for depressive conditions. Other than Olsen's review of the 1938-9 British supplementation of halibut liver oil, I have seen no reference to the use of Omega 3 oils and the duration of labour. In Canada where I work, women typically consume little fish in pregnancy. I have been recommending 4 g of Omega 3 oils (fish / flax / evening primrose oil) throughout pregnancy and have not found increased pre-term delivery rates. While my evidence is anecdotal, I have however, found that the ingestion of 4 gm (up to 8 g daily for larger women)of Omega 3 oils results in a significant reduction in the length of labour. Primiparous women who could be expected to experience 12 hours of active labour typically labour for 6 hours or less, a significant reduction. Can you comment on the subject of a reduced duration of labour with increased Omega 3 intake in pregnancy? Also, if fish oils prolong the duration of pregnancy, it is recommended to reduce supplementation at term to avoid post-term pregnancy? What contraindications, if any, are there to fish oil supplementation in pregnancy? Am I right in assuming that Omega 3 supplementation should increase in muliple pregnancies and lactation? How much is too much? My understanding is that the Canadian government recommends a minimum of 250 mg of DHA daily in pregnancy - what would be an average recommended intake?
Is it really due to sea food? 27 February 2002
Valmiki Kolmi Nagaraj, Specialist registrar SWDHA, Dartington, Anandhi Nagaraj Send response to journal: Re: Is it really due to sea food?	The authors have made a good effort to study the effect of seafood in early preganancy on preterm delivery but the validity of the results are questionable. Though the tool used i.e the food frequency questionaire be used to quanitify the intake of seafood will it give an accurate estimate of long chain fatty acids especially to study a dose response relationship? Further, deatils of consumption of other food stuff including the protein intake and caloric intake, which may themselves affect birthweight are not given. A nested case control study using preterm delivery and low birth weight as cases and matched controls could have been more informative in this case.
Antenatal care and sea fish 11 March 2002
Michel R Odent, Director. Primal Health Research Centre 72, Savernake road. London NW3 2JR, Paul A De Reu and Suzanne Colson Send response to journal: Re: Antenatal care and sea fish	Should we routinely encourage all pregnant women to consume sea fish or to increase their consumption of sea fish? This is the main practical question inspired by the Danish study (1). In 1991-1992, in the antenatal clinic of an East London hospital (Whipps Cross hospital), we randomly encouraged 499 pregnant women (before 20 weeks) to increase their consumption of sea fish. For each woman a parity matched control was established. We could not detect any significant effect of our dietary recommendations in the perinatal period in terms birthweight and duration of pregnancy (2). The rate of prematurity was 34/468 in the study group versus 44/462 in the control group (95% CI 0.45-1.2). We repeated similar studies in three different contexts: a French University hospital (Rennes), a Dutch midwifery practice (Boxtel) and another East London hospital (Newham). We were not encouraged to enlarge these studies because, once more, significant effects could not be detected in the perinatal period. In the cumulative study group, the rate of prematurity was 23/538 (4.27%). In the control group it was 22/555 (3.96%). One must underline that the Danish study assessed dietary habits that preceded to a great extent the beginning of pregnancy. It is probable that dietary recommendations in antenatal clinics occur too late to have detectable effects in the perinatal period. We should not conclude that such recommendations are useless. We must keep in mind the issues of milk content in highly polyunsaturated fatty acids and brain development. It is noticeable that in the Whipps Cross study the measure of head circumference at birth provided the only detectable difference between the two groups (mean 34.65 cm versus 34.45 cm. 95% CI 0.01-0.39). References: 1- Olsen S, Secher NJ. Low consumption of seafood in early pregnancy as a risk factor for preterm delivery: prospective cohort study. BMJ 2002; 324:447 (23 February) 2- Odent MR, McMillan L, Kimmel T. Prenatal care and sea fish. European Journal of Obstetrics & Gynecology and Reproductive Biology 1996; 68: 49-51
The safety of eating fish during pregnancy needs to be determined 12 March 2002
Roger A Harrison, NHS Research Fellow Wigan and Bolton Health Authority, 61 Standishgate, Wigan WN1 1AH, Lee Hooper Send response to journal: Re: The safety of eating fish during pregnancy needs to be determined	Sir A prospective study reported that eating fish during pregnancy increased gestation and reduced low birth weight (1). We wish to raise several important points arising from this study. The current analysis is restricted to singleton, live-born babies without detected malformations. Hence, there is no information on the overall safety of eating fish during pregnancy. Fish is a major source of polychlorinated biphenyls, methyl mercury and dioxins, which may be harmful during and following pregnancy (2). Moreover, one cannot assume that the observed benefits reported here were from eating fish. Lack of fish consumption was part of a lifestyle pattern as these women were more likely to be disadvantaged in terms of smoking status, level of education, being unpartnered, small, light and teenaged. It is likely that other dietary and lifestyle issues will vary by fish consumption and complete adjustment for confounders is impossible. This has been the case with beta -carotene (3) where randomised controlled trials failed to support benefits previously found in cohort studies. The methods used to estimate the intake of n-3 in this study probably resulted in misclassification. This will attenuate risk estimates making it difficult to determine the minimum beneficial dose. However, this would suggest that the ‘true’ benefit from eating fish is greater than that observed. The main concern is with using a fixed estimate of n-3 content for each fish meal (hot fish meal, fish sandwich and fish salad). This assumes that different species of fish contain similar amounts of n-3. However, this can vary up to 16-fold across different species (4). For example, 100g of haddock contains 0.16g of n-3 while 100g of pilchards contains 2.60g of n-3. A more reliable estimate of the intake of n-3 would have been obtained by summing the frequency that each species of fish was consumed, by the expected content of n-3 in that particular species of fish. This would also have been enhanced by including information on portion size in the calculation. Randomised controlled trials are needed “to examine the dose-response relationship between long-chain n-3 fatty acids and timing of delivery and preterm risk”. These should enrol women of child-bearing age in the very early stages of pregnancy. Dietary assessments need to be repeated several times to record changes in diet during pregnancy and the incorporation of biomarkers should be considered. Stillbirths, spontaneous abortion rates and outcomes relating to child development through to adulthood should be measured. Roger A Harrison NHS Research Fellow Wigan and Bolton Health Authority Lee Hooper Research Fellow in Evidence Based Practice University of Manchester. References 1. Olsen SF, Secher NJ. Low consumption of seafood in early pregnancy as a risk factor for preterm delivery: prospective cohort study. BMJ. 2002; 324: 1-5. 2. Dewailly È, Ayotte P, Blanchet C, et al (1996) Weighing contaminant risks and nutrient benefits of country food in Nunavik. Artic Med Res 55: 13-19. 3. Egger M, Shneider M, Davey Smith G. Spurious precision? Meta- analysis of observational studies. BMJ 1998;316:140-44 4. MAFF (1998) Fatty Acids. Seventh supplement to the Fifth Edition of McCance & Widdowson's "The composition of foods". Royal Society of Chemistry/MAFF: Cambridge.
Those do not eat sea food also selective in other dishes 26 April 2002
Clayman ZK Zhang, Research Staff MRC Environmental Epidemiology Unit,Southampton,SO16 6YD Send response to journal: Re: Those do not eat sea food also selective in other dishes	This report is perhaps biased by the fact that those who do not eat sea food frequently also are selective about other long chain fatty acid dishes. In the first stage of data presentation, the eating habit should be described in detail to exclude the possibility of food selections. Second,what is the main cause of reterm delivery? It cannot be simply ascribed to a simple statistical correlated factor. Perhaps there are many, and sea food is the most unimportant one. So the fact might be that more direct factors have not yet been discovered.