Fish-oil and pre-eclampsia

Dietary fat intake with risk of gestational diabetes mellitus and preeclampsia: a systematic review and meta-analysis of prospective cohort studies

CONTEXT

Gestational diabetes mellitus (GDM) and preeclampsia (PE) are commonly observed medical complications in pregnancy. Dietary total fat and fatty acids associated with GDM and PE risk have been examined in several epidemiological studies. In some instances, systematic reviews and meta-analyses might provide more accurate dietary recommendations.

OBJECTIVES

This systematic review and dose-response meta-analysis was conducted to investigate the association between dietary total fat and fatty acids and the risk of GDM and PE.

DATA SOURCES

Research on dietary fat intake and the risk of GDM and PE was conducted through systematic searches of the PubMed, Scopus, and Web of Science databases for articles published up to August 19, 2023. An investigation of associations between dietary intake of total fat and fatty acids and the risk of GDM and PE was performed using prospective cohort study designs.

RESULTS

Twenty-one prospective cohort studies were considered eligible. Findings indicated that higher intakes of total fat (relative risk [RR], 1.08; 95% confidence interval [CI], 1.02-1.14), animal fat (RR, 1.56; 95%CI, 1.34-1.89), vegetable fat (RR, 1.23; 95%CI, 1.05-1.45), dietary cholesterol (RR, 1.48; 95%CI, 1.10-2.00), and omega-3 fatty acid (RR, 1.11; 95%CI, 1.02-1.20) are associated with a greater risk of GDM. However, no significant association was found between dietary total fat and fatty acids and the risk of PE. Dose-response meta-analyses suggested every 10% increment in total energy intake from total fat, 5% from animal fat, 5% from vegetable fat, and 100 mg from cholesterol was related to 15%, 12%, 7%, 14%, and 20% higher GDM risk, respectively.

CONCLUSIONS

Overall, total fat, animal fat, vegetable fat, dietary cholesterol, and omega-3 fatty acid consumption are associated with a small but statistically significant increase in GDM risk.

PROTOCOL REGISTRATION

PROSPERO (CRD42023466844).

Does eating oily fish improve gestational and neonatal outcomes? Findings from a Sicilian study

BACKGROUND

Fish is a source of long-chain polyunsaturated n-3 fatty acids, but it may also contain a number of pollutants.

METHODS

Between April and July 2013, we selected 114 women who gave birth to living babies, and divided them according to type and frequency of the fish consumed. We evaluated both gestational and neonatal outcomes. Docosahexaenoic acid (DHA) supplementation was taken into account.

FINDINGS

One hundred and four women (91.2%) consumed fish on the average of 4.7 times/month, while 10 (8.8%) did not consume fish at all. Fifty-nine women (51.8%) were taking supplements containing DHA (200mg/day), almost all of whom (n=55) consumed fish. Pregnancy induced hypertension was more frequent in non-fish eaters than in fish eaters (20% vs 4.8%, P=0.056). Consumption of small size oily fish correlated positively with both neonatal weight (r=0.195, P=0.037) and head circumference (r=0.211, P=0.024). In contrast, consumption of lean fish or shellfish correlated negatively with neonatal head circumference (r=0.206, P=0.028, or r=0.192, P=0.041).

DISCUSSION

These data agree with previous observational studies and reinforce the protective role of small oily fish consumption on preterm birth risk, neonatal weight, length and head circumference.

CONCLUSION

Small oily fish consumption should be favored over other types of fish.

Preeclampsia: pathophysiology and implications for care

Nurses are increasingly encountering pregnant/postpartum women with hypertensive disorders of pregnancy, of which preeclampsia is one of the most common. The Joint Commission published a Sentinel Event Alert in 2010 on prevention of maternal death. This report notes that one of the 5 leading causes of pregnancy-related mortality between 1991 and 1997 was "hypertensive disorder." Preeclampsia presents significant risk to the health of the mother and the fetus. Clearly, nurses must understand the pathophysiology, assessment, management, recurrence risk, and long-term implications of preeclampsia to participate fully in a management plan that promotes safe patient care.

Role of nutrition in the risk of preeclampsia

Preeclampsia (PE) accounts for about one-quarter of the cases of maternal mortality and ranks second among the causes of pregnancy-associated maternal deaths in Canada and worldwide. The identification of an effective strategy to prevent PE is a priority and a challenge for research in obstetrics. Progress has been hampered by inadequate understanding of the underlying etiology of the disease. The role of maternal diet in the etiology of PE has recently received increased attention. The objective of this paper is to provide an overview of the literature concerning 1) the current understanding of the pathogenesis of PE, 2) the biological plausibility and potential mechanisms underlying the associations between maternal dietary exposures, nutrition, and the risk of PE, and 3) the epidemiological findings of maternal nutrient intake in relation to the risk of PE.

Effect of Placental Fatty Acid Metabolism and Regulation by Peroxisome Proliferator Activated Receptor on Pregnancy and Fetal Outcomes

Fatty acids, particularly the omega-3 and omega-6 essential fatty acids (EFAs), are considered critical nutritional sources for the developing fetus. The placenta governs the fetal supply of fatty acids via two processes: transport and metabolism. Placental fatty acid metabolism can play a critical role in guiding pregnancy and fetal outcome. EFAs can be metabolized to important cell signaling molecules in placenta by several major isoform families including: the Cytochrome P450 subfamily 4A (CYP4A); Cyclooxygenases (COXs); and Lipoxygenases (LOXs). Peroxisome proliferator-activated nuclear receptors (PPARs) have been demonstrated to regulate a number of placental fatty acid/lipid homeostasis-related proteins (e.g., metabolizing enzymes and transporters). The present review summarizes research on the molecular and functional relevance of fatty acid metabolizing enzymes and the role of PPARs in regulating their expression in the mammalian placenta. Elucidating the pathways of placental fatty acid metabolism and the regulatory processes governing these pathways is critical for advancing our understanding of the role of placenta in supplying EFAs to the developing fetus and the potential implications on pregnancy and fetal outcome. A more complete understanding of placental fatty acid disposition may also provide a basis for nutritional/pharmacological interventions to ameliorate the risk of adverse pregnancy and/or fetal outcomes.

Diet during pregnancy and risk of preeclampsia or gestational hypertension

PURPOSE

We sought to examine associations of first-trimester intake of calcium, n-3 and n-6 fatty acids, trans fatty acids, magnesium, folate, and vitamins C, D, and E with preeclampsia (PE) and gestational hypertension (GH).

METHODS

We studied associations of diet with PE or GH among 1718 women in the prospective cohort study Project Viva, using logistic regression and adjusting for maternal age, prepregnancy body mass index, first trimester systolic blood pressure, race/ethnicity, education, and parity. We assessed first-trimester diet using a validated semiquantitative food frequency questionnaire.

RESULTS

A total of 59 (3%) women developed PE, and 119 developed (7%) GH. We found a somewhat-lower risk of PE associated with higher intake of the elongated n-3 fatty acids docosahexaenoic and eicosapentaenoic acids (odds ratio [OR] 0.84, 95% confidence interval [95% CI]: 0.69-1.03 per 100 mg/day), fish (OR 0.91, 95% CI 0.75-1.09 per serving/day), and the ratio of docosahexaenoic + eicosapentaenoic to arachadonic acid (OR 0.82, 95% CI 0.66-1.01). We did not observe a lower risk of GH or PE with a greater intake of calcium; vitamin C, D, or E; milk; magnesium; folate; or with lower intake of n-6 or trans fatty acids.

CONCLUSIONS

Our results support a potential benefit for elongated n-3 fatty acids in preventing preeclampsia.

Does fish oil prevent preterm birth?

A literature review was performed on the effect of fish oil on preterm birth in observational and randomized studies. The only weak effect on preterm birth found in meta-analyses could be caused by the low compliance, and the fact that many women stop supplementation before term together with a fast acting effect on fish oil.

Gestational age and birth weight in relation to n-3 fatty acids among Inuit (Canada)

Seafood consumption during pregnancy carries both benefits (high n-3 FA intake) and risks (exposure to environmental contaminants) for the developing fetus. We determined the impacts of marine n-3 FA and environmental contaminants on gestational age (GA) of Nunavik women and the anthropometric characteristics of their newborns. FA and contaminant (polychlorinated biphenyls and mercury) concentrations were measured in cord plasma of Nunavik newborns (n = 454) and compared with those of a group of newborns (n = 29) from southern Québec. Data were collected from hospital records and birth certificates. In Nunavik newborns, arachidonic acid (AA) was two times lower (P < 0.0001), whereas DHA concentration, the sigman-3 / sigman-6 ratio, and the percentage of n-3 highly unsaturated FA (HUFA) (of the total HUFA) were three times higher (P < 0.0001) compared with southern Québec newborns. After controlling for confounders, GA and birth weight were higher by 5.4 d [95% confidence interval (CI): 0.7-10.1] and 77 g (95% CI: -64 to 217) in the third tertile of percentage of n-3 HUFA (of the total HUFA) as compared with the first tertile. There was no evidence that contaminants had negative effects on GA or birth weight. In this seafood-eating population, an increase in the proportion of n-3 HUFA (of the total HUFA), measured in umbilical cord plasma phospholipids, was associated with a significantly longer GA.

Nutritional interventions during pregnancy for the prevention or treatment of maternal morbidity and preterm delivery: an overview of randomized controlled trials

This overview assesses the effectiveness of nutritional interventions to prevent or treat maternal morbidity, mortality and preterm delivery. Cochrane systematic reviews and other up-to-date systematic reviews and individual randomized controlled trials were sought. Searches were carried out up to July 2002. Iron and folate supplements reduce anemia and should be included in antenatal care programs. Calcium supplementation to women at high risk of hypertension during pregnancy or low calcium intake reduced the incidence of both preeclampsia and hypertension. Fish oil and vitamins E and C are promising for preventing preeclampsia and preterm delivery and need further testing. Vitamin A and beta-carotene reduced maternal mortality in a large trial; ongoing trials should provide further evaluation. No specific nutrient supplementation was identified for reducing preterm delivery. Nutritional advice, magnesium, fish oil and zinc supplementation appear promising and should be tested alone or together in methodologically sound randomized controlled trials. Anema in pregnancy can be prevented and treated effectively. Considering the multifactorial etiology of the other conditions evaluated, it is unlikely that any specific nutrient on its own, blanket interventions or magic bullets will prevent or treat preeclampsia, hemorrhage, obstructed labor, infections, preterm delivery or death during pregnancy. The few promising interventions for specific outcomes should be tested or reconsidered when results of ongoing trials become available. Until then, women and their families should receive support to improve their diets as a general health rule, which is a basic human right.

Nutrient intake and hypertensive disorders of pregnancy: Evidence from a large prospective cohort

OBJECTIVE

The objective of this analysis was to prospectively determine the effects of nutrient intakes on the incidences of preeclampsia and pregnancy-associated hypertension among women enrolled in the Calcium for Preeclampsia Prevention study.

STUDY DESIGN

This was a prospective observational cohort study of women in a randomized clinical trial that included women seeking prenatal care at university medical centers and affiliated clinics and hospitals in 5 US communities. A total of 4589 nulliparous women were recruited between 13 and 21 weeks' gestation. Preeclampsia and pregnancy-associated hypertension were the main outcome measures.

RESULTS

Preeclampsia was noted in 326 (7.6%) of the 4314 women with known pregnancy outcomes followed up until > or =20 weeks' gestation, and pregnancy-associated hypertension was noted in 747 (17.3%). As previously reported, there was no significant difference in these outcomes between cohorts randomly assigned to supplementation with calcium or placebo. By means of logistic regression a baseline risk model was constructed for preeclampsia and pregnancy-associated hypertension. After adjustment for treatment and clinical site, body mass index >26 kg/m(2) and race were significantly associated with an increased risk of preeclampsia. Body mass index > or =35 kg/m(2), race, and never smoking were significantly associated with an increased risk of pregnancy-associated hypertension. After adjustment for baseline risks, none of the 28 nutritional factors analyzed were significantly related to either preeclampsia or pregnancy-associated hypertension.

CONCLUSION

We found no evidence in this study for a significant association of hypertensive disorders of pregnancy with any of the 23 nutrients measured.

Randomised clinical trials of fish oil supplementation in high risk pregnancies. Fish Oil Trials In Pregnancy (FOTIP) Team

OBJECTIVE

To test the postulated preventive effects of dietary n-3 fatty acids on pre-term delivery, intrauterine growth retardation, and pregnancy induced hypertension.

DESIGN

In six multicentre trials, women with high risk pregnancies were randomly assigned to receive fish oil (Pikasol) or olive oil in identically-looking capsules from around 20 weeks (prophylactic trials) or 33 weeks (therapeutic trials) until delivery.

SETTING

Nineteen hospitals in Europe.

SAMPLES

Four prophylactic trials enrolled 232, 280, and 386 women who had experienced previous pre-term delivery, intrauterine growth retardation, or pregnancy induced hypertension respectively, and 579 with twin pregnancies. Two therapeutic trials enrolled 79 women with threatening pre-eclampsia and 63 with suspected intrauterine growth retardation.

INTERVENTIONS

The fish oil provided 2.7 g and 6.1 g n-3 fatty acids/day in the prophylactic and therapeutic trials, respectively.

MAIN OUTCOME MEASURES

Preterm delivery, intrauterine growth retardation, pregnancy induced hypertension.

RESULTS

Fish oil reduced recurrence risk of pre-term delivery from 33% to 21% (odds ratio 0.54 (95% CI 0.30 to 0.98)) but did not affect recurrence risks for the other outcomes (OR 1.26; 0.74 to 2.12 and 0.98; 0.63 to 1.53, respectively). In twin pregnancies, the risks for all three outcomes were similar in the two intervention arms (95% CI for the three odds ratios were 0.73 to 1.40, 0.90 to 1.52, and 0.83 to 2.32, respectively). The therapeutic trials detected no significant effects on pre-defined outcomes. In the combined trials, fish oil delayed spontaneous delivery (proportional hazards ratio 1.22; 1.07 to 1.39, P = 0.002).

CONCLUSIONS

Fish oil supplementation reduced the recurrence risk of pre-term delivery, but had no effect on pre-term delivery in twin pregnancies. Fish oil had no effect on intrauterine growth retardation and pregnancy induced hypertension, affecting neither recurrence risk nor risk in twin pregnancies.

Long-chain polyunsaturated fatty acids, pregnancy, and pregnancy outcome

During pregnancy, essential long-chain polyunsaturated fatty acids (LCPUFAs) play important roles as precursors of prostaglandins and as structural elements of cell membranes. Throughout gestation, accretion of maternal, placental, and fetal tissue occurs and consequently the LCPUFA requirements of pregnant women and their developing fetuses are high. This is particularly true for docosahexaenoic acid (DHA; 22:6n-3). The ratio of DHA to its status marker, docosapentaenoic acid (22:5n-6), in maternal plasma phospholipids decreases significantly during pregnancy. This suggests that pregnancy is associated with maternal difficulty in coping with the high demand for DHA. The DHA status of newborn multiplets is significantly lower than that of singletons; the same is true for infants of multigravidas as compared with those of primigravidas and for preterm compared with term neonates. Because the LCPUFA status at birth seems to have a long-term effect, the fetus should receive an adequate supply of LCPUFAs. Data from an international comparative study indicated that, especially for n-3 LCPUFAs, the fetus is dependent on maternal fatty acid intake; maternal supplementation with LCPUFAs, their precursors, or both increased LCPUFA concentrations in maternal and umbilical plasma phospholipids. However, significant competition between the 2 LCPUFA families was observed, which implies that effective supplementation requires a mixture of n-6 and n-3 fatty acids. Further research is needed to determine whether higher LCPUFA concentrations in plasma phospholipid will have functional benefits for mothers and children.

Optimality of the birth population reduces learning and behaviour disorders and sudden infant death after the first month

The weight distribution pattern of all births can be divided into a "skewing to the left" to lower weights and high neonatal mortality, a "skewing to the right" to higher weights (>3500g) and minimum neonatal and postneonatal mortality, and a "symmetrical distribution" with mortality in between. This study was initiated with the hypothesis that a deficit in newborns of more than 3500 g would adversely affect postneonatal death. Higher and rising postneonatal mortality solely attributable to sudden infant death of unknown cause (sudden infant death syndrome; SIDS) was observed in the Nordic countries with a lower proportion of heavy newborns. Minor environmental intervention almost eliminated excess mortality from this cause, supporting raised susceptibility with a depressed birthweight in postneonatal SIDS. This contrasts with classical neonatal low birthweight SIDS, which is stable despite numerous attempts at reduction, supporting a multi-factorial aetiology: low maternal age, low education, low socioeconomic status, maternal smoking, infection, etc. The postneonatal SIDS epidemic associated with a deficit in heavy newborns is thought to be a result of changing behaviour in pregnancy: moderate iatrogenic dietary restriction and young women favouring a low-calorie, low-fat diet, especially in the third trimester when the foetus is most vulnerable, which delays myelination and somatic growth and renders the infant susceptible to minor morbidity and irregularity. The timing of death and neuropathological findings suggestive of repeated hypoxic episodes in more than 80% of cases of SIDS prior to death support this theory. The similar weight distribution patterns in SIDS and all births in Denmark, the UK and the USA suggest a substantial proportion of the neonates in these countries could be growth-retarded and at risk of hypoxic episodes in infancy. A few cases, particularly males (sex-ratio = 1.7), suffer SIDS, the majority survive. Many, mostly males, present minor CNS signs and learning and behaviour problems. The male predominance accords with males more than 500 g higher optimal birthweight than females and susceptibility to a depressed weight at birth. In order to prevent postneonatal dying, SIDS and reduce learning/behaviour disorders it is necessary to raise the proportion of heavy newborns by promoting foetal growth rate equal to the maternal intrinsic rate by eating to one's appetite a balanced diet, favouring a diet high in marine fat, especially in third trimester, in order to ensure maturation of the CNS and prolong gestation, thereby increasing birthweight. Although the increased survival of some very low birthweight neonates confounds the issue, a division between SIDS in neonatal and postneonatal death is recommended in order to assess the proportion of "avoidable infant death" as opposed to persistent classical neonatal SIDS.

Growth, development and differentiation: a functional food science approach

Few other aspects of food supply and metabolism are of greater biological importance than the feeding of mothers during pregnancy and lactation, and of their infants and young children. Nutritional factors during early development not only have short-term effects on growth, body composition and body functions but also exert long-term effects on health, disease and mortality risks in adulthood, as well as development of neural functions and behaviour, a phenomenon called 'metabolic programming'. The interaction of nutrients and gene expression may form the basis of many of these programming effects and needs to be investigated in more detail. The relation between availability of food ingredients and cell and tissue differentiation and its possible uses for promoting health and development requires further exploration. The course of pregnancy, childbirth and lactation as well as human milk composition and the short- and long-term outcome of the child are influenced by the intake of foods and particularly micronutrients, e.g. polyunsaturated fatty acids, Fe, Zn and I. Folic acid supplementation from before conception through the first weeks of pregnancy can markedly reduce the occurrence of severe embryonic malformations; other potential benefits of modulating nutrient supply on maternal and child health should be further evaluated. The evaluation of dietary effects on child growth requires epidemiological and field studies as well as evaluation of specific cell and tissue growth. Novel substrates, growth factors and conditionally essential nutrients (e.g. growth factors, amino acids, polyunsaturated fatty acids) may be potentially useful as ingredients in functional foods and need to be assessed carefully. Intestinal growth, maturation, and adaptation as well as long-term function may be influenced by food ingredients such as oligosaccharides, gangliosides, high-molecular-mass glycoproteins, bile salt-activated lipase, pre- and probiotics. There are indications for some beneficial effects of functional foods on the developing immune response, for example induced by antioxidant vitamins, trace elements, fatty acids, arginine, nucleotides, and altered antigen contents in infant foods. Peak bone mass at the end of adolescence can be increased by dietary means, which is expected to be of long-term importance for the prevention of osteoporosis at older ages. Future studies should be directed to the combined effects of Ca and other constituents of growing bone, such as P, Mg and Zn, as well as vitamins D and K, and the trace elements F and B. Pregnancy and the first postnatal months are critical time periods for the growth and development of the human nervous system, processes for which adequate substrate supplies are essential. Early diet seems to have long-term effects on sensory and cognitive abilities as well as behaviour. The potential beneficial effects of a balanced supply of nutrients such as I, Fe, Zn and polyunsaturated fatty acids should be further evaluated. Possible long-term effects of early exposure to tastes and flavours on later food choice preferences may have a major impact on public health and need to be further elucidated. The use of biotechnology and recombinant techniques may offer the opportunity to include various bioactive substances in special dietary products, such as human milk proteins, peptides, growth factors, which may have beneficial physiological effects, particularly in infancy and early childhood.

Drug management of hypertensive disorders of pregnancy

Drugs used in the acute and long-term management of hypertension in pregnancy and the preeclampsia-eclampsia syndrome have been reviewed and their therapeutic effects and maternal and fetal adverse effects have been considered. The review also focuses on recent developments in the areas of prevention and management of pre-eclampsia-eclampsia syndrome. Although a number of new drugs have emerged, as potentially useful in the management of hypertension in pregnancy and pre-eclampsia-eclampsia syndrome, some remain at the cornerstone of therapy; for example, methyldopa for long-term treatment of chronic hypertension, hydralazine or nifedipine for rapid reduction of severely elevated blood pressure, and magnesium sulphate for eclampsia. Some of these agents, especially the calcium antagonists, show promise in that their use is associated with fewer side effects. Safety for the fetus, however, has not been adequately evaluated yet. Neither aspirin nor calcium supplements appear to improve the outcome in pregnancy. Currently, the dilemma whether to treat hypertension in pregnancy and pre-eclampsia-eclampsia syndrome with old, established, cost-effective drugs or the promising newer drugs provides an interesting academic challenge.

Optimal foetal growth in the reduction of learning and behaviour disorder and prevention of sudden infant death (SIDS) after the first month

A theory is presented that a diet low in polyunsaturated fatty acids (PUFA) in the third trimester of pregnancy may delay myelination and brain maturation. This may underpin learning and behaviour disorders and sudden infant death (SIDS) after the first month, conditions that are associated with lower than average birthweight. Epidemiological evidence is reviewed showing an inverse relation between the proportion of heavy newborns (> 3500 g) and infant mortality rate. Some countries with a lower proportion of heavy newborns despite equally high standards of living and medical care have higher post-neonatal death rates. The higher rates are solely due to SIDS which has a peak mortality within 80-100 days. It is hypothesised that as this is a time when myelination peaks, SIDS may be due to maturational delay. Evidence of subtle CNS changes in brainstem structures and in the neuromuscular system supports an instability in brainstem control systems. Moderate iatrogenic dietary restriction predominates today, but a rising number of women favour a low-caloric low-fat diet especially in the third trimester when the foetus is most susceptible. This may lead to a depressed birthweight, delayed somatic growth and neuronal maturation, such as is observed in SIDS victims. The majority exposed to suboptimal conditions survive, but a few suffer SIDS; confirming post-neonatal susceptibility. Many, especially males, present minor CNS signs and learning/behaviour disorders that could be the sequelae of repeated hypoxic episodes, such as recorded in more than 80% of SIDS victims. To reduce learning/behaviour disorders and prevent death from SIDS after the first month, it is necessary to ensure optimal development by promoting foetal growth. It is advised to avoid unnecessary dieting and to favour a diet high in PUFAs, thus prolonging pregnancy and so increasing birthweight.

Magnesium taurate for the prevention and treatment of pre-eclampsia/eclampsia

The use of parenteral magnesium sulfate for the management of pre-eclampsia/eclampsia is well established. In striking analogy to the effects of hypermagnesemia, taurine has antivasospastic, antihypertensive, platelet-stabilizing, anticonvulsant and hypoxia-protective properties. Thus parenteral magnesium taurate can reasonably be proposed as a superior alternative to magnesium sulfate in the treatment of pre-eclampsia; administered orally as a component of prenatal supplementation, magnesium taurate might well have both preventive and therapeutic value in this syndrome. In the light of the hypoxia-protective actions of both magnesium and taurine, such supplementation might also protect fetuses experiencing temporary perinatal asphyxia, lessening the risk of cerebral palsy.

The effect of high dietary n-3 fatty acid supplementation on angiotensin II pressor response in human pregnancy

OBJECTIVE

Our purpose was to evaluate the effects of n-3 fatty acid supplementation on vascular reactivity as measured by the angiotensin II sensitivity test.

STUDY DESIGN

Ten subjects with uneventful pregnancies, who were free of any chronic medical illnesses, between 24 and 34 weeks' gestation participated. Each subject was provided with OMEGA-3 700 softgel capsules and instructed to take three tablets three times daily (approximately 3.6 gm of eicosapentaenoic acid). The angiotensin II sensitivity test was performed before and 28 days after supplementation. Compliance was assessed by analysis of computerized pill bottles. Statistical analyses of the data were performed with a paired t test for evenly distributed continuous data. A sample size of eight patients was required to detect a difference in effective pressor dose of > or = 10 ng/kg/min between the presupplement and postsupplement results, assuming an alpha of 0.05 and a beta of 0.20 (80% power).

RESULTS

The effective pressor dose before treatment (13.6 +/- 6.3 ng/kg/min) (mean +/- SD) was significantly less (p = 0.001) than after supplementation (35.8 +/- 15.9 ng/kg/min).

CONCLUSIONS

High-dose n-3 fatty acid supplementation resulted in an enhancement of the pregnancy-acquired refractoriness to angiotensin II.

Effects of fish oil supplementation in late pregnancy on blood pressure: a randomised controlled trial

OBJECTIVE

To study the effect of fish oil supplementation on blood pressure during the third trimester of pregnancy.

DESIGN

In the 30th week of pregnancy 533 healthy women were randomly assigned in a ratio 2:1:1 to receive fish oil (2.7 g/day n-3 fatty acids (Pikasol)), or a control regimen of either olive oil or no oil supplementation.

MAIN OUTCOME MEASURES

Blood pressure measured with an automatic device (Dinamap 1846 SX, Criticon) at baseline and in weeks 33, 37, 39 and subsequently weekly until delivery.

RESULTS

Mean blood pressure increased during the third trimester, and this was not influenced by group assignment. No significant effects on either systolic or diastolic blood pressure were seen in the fish oil group compared to the control groups. The proportions of women with a systolic blood pressure above 140 mmHg or a diastolic blood pressure above 90 mmHg were not significantly different in the fish oil group compared with the control groups, although the proportion of women with diastolic above 90 mmHg tended to be lower in the fish oil group compared with the olive oil group. The corresponding relative risk was RR = 0.48 (95% CI 0.22-1.06; P = 0.07).

CONCLUSION

2.7 g/day of marine n-3 fatty acids provided in the third trimester of normal pregnancy showed no effect on blood pressure.

Complexity and complicity in eclampsia: barriers or bridges?

The aetiology of pre-eclampsia-eclampsia remains largely unclarified, despite over 100 years of systematic study. The assumption that the triggering event is linear and amenable to reductionist techniques has characterized these efforts. The main purpose of this paper is to show that complexity and complicity characterize most pathophysiological processes in pre-eclampsia-eclampsia, a situation suggesting that similar mechanisms must exist at the origin of the disease. The unique configuration of the intervillous space and the intensity of energy transference through the fetomaternal interface offer many dysfunctional possibilities, even in clinically normal pregnancies. The most characteristic seem to be: the shedding and deportation of trophoblast, the fragmentation of villi, the escape of fetal blood, and events associated with trophoblast damage, degeneration and death. The pathogenic potential of these natural processes seems to depend on the association with amplifiers and permissive factors, which vary from person to person and from time to time. Thus, considering the convergence of multiple factors and the presence of nonlinearity in some of their interactions as a plausible working hypothesis, further exploration on this subject should adhere to the rules of this different reality. To find the best possible method of inquiry and to recognize its limitations will be the surest way to avoid failure.

Essential fatty acid status in neonates after fish-oil supplementation during late pregnancy

Healthy pregnant women (n 23) were supplemented with fish-oil capsules (2.7 g n-3 polyunsaturated fatty acids/d) from the 30th week of gestation until delivery. Subjects in a control group were either supplemented with olive-oil capsules (4 g/d, n 6) or received no supplementation (n 10). Fatty acid compositions of the phospholipids isolated from umbilical plasma and umbilical arterial and venous vessel walls were determined. Fatty acid compositions of maternal venous plasma phospholipids were determined as well. Maternal plasma phospholipids of the fish-oil-supplemented group contained more n-3 fatty acids and less n-6 fatty acids. Moreover, the amounts of the essential fatty acid deficiency markers Mead acid (20:3n-9) and Osbond acid (22:5n-6) were significantly lower. The extra amount of n-3 fatty acids consumed by the mothers resulted in higher contents of n-3 fatty acids, and of docosahexaenoic acid (22:6n-3) in particular, in the phospholipids of umbilical plasma and vessel walls. It is, indeed, possible to interfere with the docosahexaenoic acid status at birth: children born to mothers supplemented with fish oil in the last trimester of pregnancy start with a better docosahexaenoic acid status at birth, which may be beneficial to neonatal neurodevelopment.

Possible dietary measures in the prevention of pre-eclampsia and eclampsia

The recurring theme when considering the various dietary manipulations that have been advocated in the prevention of pre-eclampsia is of dietary deficiencies and excesses that appear to be associated with the disease. However, whether these deficiencies and excesses cause, or arise as a consequence of, pre-eclampsia has frequently not been established. Advocates of dietary theories of the aetiology of the disease have tended to base their claims upon uncontrolled clinical trails and inadequate research investigations. With very few exceptions, the better-designed studies have failed to show any effect of dietary supplementation or restriction on the incidence of pre-eclampsia. While certain manipulations, for example calcium and n-3 fatty acid supplementation seem intriguing and merit further study, potentially harmful effects of other manipulations, namely weight restriction (Campbell Brown, 1983), salt restriction (Robinson, 1958) and magnesium supplementation (Lamm et al, 1988), have been demonstrated. The persistent tendency for the medical profession to provide dogmatic and often conflicting advice, and to advocate rigorous intervention, is thus culpable. Until the appropriate research is performed in a less haphazard fashion, with all interventions performed in the context of controlled trials, no dietary intervention can be advocated.

Maternal essential fatty acid patterns during normal pregnancy and their relationship to the neonatal essential fatty acid status

Although essential fatty acids (EFA) and their longer chain, more unsaturated derivatives play a major role during pregnancy, hardly any information is available with respect to the course of the maternal EFA status during an uncomplicated pregnancy and its relationship to the neonatal EFA status. Therefore, a longitudinal study was started in which 110 pregnant women gave repeated blood samples from the 10th week of gestation until delivery. After birth a blood sample from the umbilical vein and a maternal venous blood sample were collected as well, and 6 months after delivery a final blood sample from the mother was taken. The absolute (mg/l) and relative (% total fatty acids) amounts of the fatty acids in plasma phospholipids were determined. The total amounts of fatty acids increased significantly during pregnancy. This pattern was similar for the individual fatty acids and fatty acid families. The relative amount of linoleic acid (18:2n-6) did not change during pregnancy, whereas the relative amount of arachidonic acid (20:4n-6) decreased. Despite maternal mobilization of docosahexaenoic acid (22:6n-3, DHA), suggested by a temporary increase in the DHA status until 18 weeks gestation, the DHA status steadily declined thereafter. This pattern was associated with a progressive increase in the DHA deficiency index in maternal blood throughout pregnancy and resulted in a sub-optimal neonatal DHA status. The overall maternal EFA status also declined steadily during pregnancy. Therefore, the question arises whether the mother, under the prevailing dietary conditions, is able to meet the high fetal requirement for EFA.

The essential fatty acid status of mother and child in pregnancy-induced hypertension: a prospective longitudinal study

OBJECTIVE

Our purpose was to investigate, in a prospective way, whether the altered essential fatty acid status observed in pregnancy-induced hypertension is a consequence of the disease or may contribute to its cause.

STUDY DESIGN

Pregnant women healthy at the start of the study were asked to give a blood sample before 16 weeks, at 22 weeks, and at 32 weeks of gestation. After delivery a blood sample from the umbilical vein, a piece of the umbilical cord, and a maternal blood sample were collected. Fatty acid compositions were determined of the phospholipids isolated from plasma and umbilical arterial and venous vessel walls. The nutrient intake of the pregnant women was assessed by use of the dietary history method and food frequency questionnaires. The results of each woman with pregnancy-induced hypertension were compared with the results of three matched healthy controls.

RESULTS

During pregnancy (16 to 32 weeks) no significant differences were observed in nutrient intake and maternal plasma fatty acid composition between the group with pregnancy-induced hypertension (n = 52) and the control group (n = 156). After delivery the relative amounts of 18:2(n-6) and 18:3(n-3) in maternal plasma were significantly lower in pregnancy-induced hypertension than in normal pregnancy. This was associated with significantly higher levels of (n-6) long-chain polyenes and cervonic acid (22:6[n-3]). In comparison with the situation at 32 weeks, the postpartum cervonic acid status increased in pregnancy-induced hypertension, whereas it decreased in normal pregnancy. The cervonic acid levels in umbilical plasma phospholipids were significantly higher after pregnancy-induced hypertension than after normal pregnancy. No significant differences were observed for the fatty acid content in umbilical vessel walls.

CONCLUSION

The results indicate that the altered essential fatty acid status in pregnancy-induced hypertension is a late phenomenon and is therefore unlikely to have contributed to the pathogenesis of pregnancy-induced hypertension. Moreover, the neonatal essential fatty acid status is not negatively affected by pregnancy-induced hypertension.

A clinico-pathological classification of perinatal deaths in the Faroe Islands

OBJECTIVE

To highlight the causes of perinatal mortality in the Faroe Islands where perimortality is high according to Nordic standards.

DESIGN

Two systems were employed to classify perinatal deaths on the basis of clinico-pathological findings, one focusing on obstetrical factors and the other on fetal-neonatal factors.

SETTING

Faroe Islands. Data from Iceland were used for comparison since the two communities have many similarities, including similar birthweight distributions.

SUBJECTS

Birth and death certificates and medical and midwife files were recovered for 98 of the 102 officially recorded perinatal deaths in the Faroes during 1977-1986. Icelandic data for 1976-1985 were available in the literature.

RESULTS

The perinatal mortality rate was 13.7 per 1000 births. Obstetric factors were classified as unexplained, congenital anomaly, antepartum haemorrhage, pre-eclampsia, mechanical causes, and maternal disorders and accounted for 43%, 18%, 15%, 11%, 6% and 6% of the 98 cases, respectively. Fetal-neonatal factors were classified as antepartum asphyxia, congenital anomaly, intrapartum asphyxia, hyaline membrane disease, pulmonary immaturity, and other causes, and these factors accounted for 43%, 18%, 15%, 9%, 5%, and 8%, respectively. The excess perinatal mortality rate of 4.1 cases per 1000 births in the Faroes, relative to Iceland, could mainly be attributed to an excess of 2.9 cases per 1000 births in the group classified as unexplained, as defined according to the obstetrics classification.

CONCLUSIONS

No well defined cause was particularly common in the Faroes or could account for the excess perinatal mortality rate in the Faroes relative to Iceland.

Erythrocyte levels compared with reported dietary intake of marine n-3 fatty acids in pregnant women

It is well established that marine n-3 fatty acids measured in erythrocyte phospholipids of non-pregnant subjects reflect the subjects' intake of these fatty acids. In 135 pregnant women in the 30th week of gestation we compared intake of marine n-3 fatty acids and energy, estimated by a combined dietary self-administered questionnaire and interview, with fatty acids measured in erythrocyte phospholipids. Daily intake (g/d) and nutrient density of marine n-3 fatty acids (mg/MJ) correlated with the n-3 fatty acid: arachidonic acid ratio (FA-ratio) with correlation coefficients of 0.48 and 0.54 respectively. In a linear regression model with three frequency questions about marine sandwiches, marine cooked meals and fish oil as explanatory variables, and the FA-ratio as dependent variable, the multiple correlation coefficient was 0.46. Conclusions from the study were (1) levels of erythrocyte fatty acids in pregnant women may be employed as a qualitative method to rank subjects according to intake of marine n-3 fatty acids; (2) with respect to the power to explain FA-ratio variability, three simple marine food frequency questions were comparable with intake of marine n-3 fatty acids assessed by an elaborate semiquantitative dietary method involving an interview.

Gestation length and birth weight in relation to intake of marine n-3 fatty acids

It has been hypothesized that marine n-3 fatty acids ingested during pregnancy prolong duration of pregnancy and increase fetal growth rate in humans. By a combined self-administered questionnaire and interview applied in the 30th week of gestation we assessed dietary intake of marine n-3 fatty acids and energy in a population-based sample of 965 pregnant Danish women; in a random 14% subsample we also measured marine n-3 fatty acids relative to arachidonic acid (FA-ratio) in erythrocytes. Mean intake of marine n-3 fatty acids was 0.25 (95% range 0-0.75) g/d. We could detect no association between n-3 fatty acid intake and FA-ratio on the one hand, and gestation length, birth weight and birth length on the other. The analyses were adjusted for maternal height, prepregnant weight, parity and smoking. The conclusion from the study was that within the intake range of this population, marine n-3 fatty acids ingested in the weeks prior to the 30th week of pregnancy seem not to be a predictor of gestation length or fetal growth rate.

Blue fish intake and percentual levels of polyunsaturated plasmatic fatty acids at labor in the mother and the newborn infant

To assess the relationship between maternal blue fish intake during pregnancy and n-3 and n-6 polyunsaturated fatty acid percentual levels in the mother and the newborn infant. Retrospective dietetic investigation at labor regarding fatty fish intake and blind plasma fatty acid analysis. Patients participants: 35 mothers and their newborn infants were studied in the Academic tertiary hospital. Mothers were classified in "blue fish high intake" group (blue fish intake > 35 g/day), intermediate intake group (12-35 g/day) and low intake group (< 12 g/day). Eleven fatty acids were analysed in plasma by means of gas chromatography. Percentual arachidonic acid levels were lower in "blue fish high intake" group mothers. Regarding the newborn infants, no differences were found concerning maternal intake. In the "intermediate intake" group of mothers, a correlation was found for maternal and fetal levels in the following fatty acids: myristic, linoleic and linolenic acids, as well as in the sum of n-6 fatty acids. Although blue fish intake influences maternal plasma levels of arachidonic acid, it does not play a decisive role in either maternal or fetal eicosapentaenoic or docosahexaenoic acid levels. Other factors need to be considered such as n-6/n-3 metabolic interaction, other nutrient composition and especially the role of placenta and fetal liver in the metabolism of polyunsaturated fatty acids.

Frequency of seafood intake in pregnancy as a determinant of birth weight: evidence for a dose dependent relationship

STUDY OBJECTIVE

The aim was to explore whether maternal consumption of seafood is a determinant of birth weight in a dose dependent manner.

DESIGN

A population based survey of lifestyle factors in pregnancy was linked with information from antenatal and obstetric records.

SETTING AND PARTICIPANTS

Seventy five per cent of all 1362 women who delivered in the Faroe Islands during the study period 1986-87 who gave a structured post partum interview on lifestyle factors.

MAIN RESULTS

Altogether, 2, 6, 16, 33, 26, 14, and 3% of women had consumed approximately 0, 1, 2, 3, 4, 5, and 6+ respectively seafood (fish or whale) dinner meals per week during pregnancy. The average birth weight (p = 0.02) and birth length (p = 0.002) varied significantly between the seven groups, and increased by about 0.2 kg and 1 cm, respectively between women who ate 0 and those who consumed 3 seafood meals per week. Mean birth weight and length tended to level off with further fish consumption: when fitting a second degree polynomial, the quadratic terms were negative and significant for both birth weight (p = 0.005) and length (p = 0.001). Analogous analyses for pregnancy duration were not significant, but exhibited similar trends. All analyses were adjusted for maternal height, weight, parity, age, marital status, and smoking.

CONCLUSIONS

The weight and length of the newborn increased with the frequency of seafood dinner meals consumed in pregnancy but only up to a consumption level of about 3 meals per week.

Effects of fish oil supplementation in the third trimester of pregnancy on prostacyclin and thromboxane production

OBJECTIVE

Disturbance in thromboxane and prostacyclin biosynthesis has been observed in preeclampsia. We studied whether fish oil supplementation in late pregnancy interferes with maternal and fetal production of thromboxane A2 and prostacyclin I2.

STUDY DESIGN

Forty-seven women in the thirtieth week of pregnancy were randomly assigned in a ratio of 2:1:1 to receive fish oil (2.7 gm of n-3 fatty acid per day [Pikasol], or either olive oil or no oil supplementation as controls. Metabolites of thromboxane A2 and A3 and of prostacyclin I2 and I3 were quantified by mass spectrometry methods in serum and urine, respectively. Maternal serum and urine were sampled at baseline, in the thirty-third and thirty-seventh weeks of pregnancy. Fetal serum was sampled at delivery.

RESULTS

At the thirty-seventh week the mean concentrations of the eicosapentaenoic-derived metabolites, thromboxane B3 and prostacyclin I3, was twofold to threefold higher (p < 0.001) in the group receiving fish oil compared with combined control groups. There were no significant effects of fish oil on the prostacyclin I2 metabolite, although there was a trend toward a reduction in thromboxane B2 in this group. In umbilical cord blood the mean concentration of thromboxane B2 was lowest in the group receiving fish oil (p = 0.03).

CONCLUSIONS

Fish oil was metabolized to the eicosapentaenoic acid-derived eicosanoids thromboxane A3 and prostacyclin I3 in pregnant women. Correspondingly, analog products of arachidonic acid tended to be depressed. It remains to be established whether these biochemical effects will prove beneficial in the prevention or treatment of preeclampsia and intrauterine growth retardation.

Reduction of thromboxane A2 synthesis in pregnancy by polyunsaturated fatty acid supplements

OBJECTIVE

High-dose supplements of fish oil reduce thromboxane synthesis in nonpregnant human subjects and were therefore proposed as a means of preventing various small-vessel disorders, including preeclampsia. The effect of fish oil on thromboxane metabolism in pregnancy was investigated in our study.

STUDY DESIGN

Sixteen normal pregnant women in the third trimester of pregnancy were treated with a daily ingestion of 6 gm fish oil capsules containing 1.6 gm of n-3 fatty acid. In five patients the treatment was stopped because of severe-flavored reflux and hiccups. Eleven patients completed 3 weeks of treatment. Twenty-four-hour urinary 11-dehydro-thromboxane B2 was measured by means of radioimmunoassay before and after completion of the study protocol in these 11 patients and in seven control pregnant women who did not receive the oil treatment.

RESULTS

A decrease ranging from 32% to 71%, in 24-hour urinary 11-dehydro-thromboxane B2 excretion (mean reduction from 1606 pg/mg creatinine to 779 pg/mg creatinine, p < 0.001) was found among the 11 fish oil-treated women. No change in excretion was found among the control women. No maternal, fetal, or neonatal bleeding disturbances occurred, and no laboratory changes in coagulation markers were observed.

CONCLUSIONS

High-dose n-3 fatty acid intake in pregnancy significantly reduces maternal thromboxane A2 synthesis. These results may provide a basis for a possible role of fish oil in managing patients at risk for preeclampsia.

Randomised controlled trial of effect of fish-oil supplementation on pregnancy duration

The high birthweights and long duration of pregnancy in the Faroe Islands led us to suggest that a high intake of marine-fat-derived n-3 fatty acids might prolong pregnancy by shifting the balance of production of prostaglandins involved in parturition. We have compared the effects on pregnancy duration, birthweight, and birth length of a fish-oil supplement, a control olive-oil supplement, and no supplementation. 533 healthy Danish women in week 30 of pregnancy were randomly assigned in a ratio of 2/1/1 to fish oil (four 1 g Pikasol capsules [containing 2.7 g n-3 fatty acids] per day), olive oil (four 1 g capsules per day), or no supplement. The three groups differed in mean length of gestation (p = 0.006), which was highest in the fish-oil group and lowest in the olive-oil group; the result was similar when the analysis was restricted to women with an estimate of gestation length based on early ultrasound findings (443 women). Pregnancies in the fish-oil group were on average 4.0 (95% confidence interval 1.5-6.4) days longer than those in the olive-oil group; the difference in birthweight was 107 (1-214) g. The effect of supplementation on length of gestation was influenced by intake of fish and of fish oil: the difference between fish-oil and other groups was increased by a low fish intake at baseline. Fish-oil supplementation in the third trimester seems to prolong pregnancy without detrimental effects on the growth of the fetus or on the course of labour.

Gestational age in relation to marine n-3 fatty acids in maternal erythrocytes: a study of women in the Faroe Islands and Denmark

Gestation is longer in Faroese than Danish women, possibly because of the high intake of marine long-chain n-3 fatty acids that down regulates formation of prostaglandins from arachidonic acid. Polyunsaturated fatty acids were quantified in erythrocytes obtained within 2 days of delivery from randomly selected groups of 62 Faroese and 37 Danish women with an assessable gestational age. Average ratio of long-chain n-3 fatty acids to arachidonic acid [(3/6) ratio] was 0.73 (SD = 0.11) in Faroese women and 0.61 (SD = 0.12) in Danish women (p less than 0.0001), corresponding to the higher intake of marine n-3 fatty acids in the Faroes. A 20% increase in the (3/6) ratio was associated with an increase in pregnancy duration of 5.7 days in Danish women (95% confidence interval, 1.4 to 10.1 days; p = 0.02) and 0.7 days in Faroese women (95% confidence interval, -2.0 to 3.3; p = 0.6). The hypothesized exposure-effect relationship may be weaker or absent at the higher level of exposure seen in the Faroese group.

A possible preventive effect of low-dose fish oil on early delivery and pre-eclampsia: indications from a 50-year-old controlled trial

A preventive effect of dietary marine n-3 fatty acids on early delivery and toxaemia has recently been hypothesized. In only one published controlled trial fish oil has been given to pregnant women, namely in that conducted during 1938-9 in London by the People's League of Health with a dietary supplement containing vitamins, minerals, and halibut liver oil. Although it was of high quality and its findings are hitherto unexplained, neglect and misinterpretation of the trial seem to occur commonly in reviews. Of the 5644 women who were enrolled the 622 withdrawals were independent of treatment. Alternate allocation to treatment was used, producing two groups that were well balanced as to age and parity. The supplement was given from about week 20. The control group did not receive any supplement. Reductions of 20.4% (95% confidence interval 9-30%, P = 0.00083) and 31.5% (95% confidence interval 11-47%, P = 0.0047) were seen in odds of delivering before 40 weeks of gestation and pre-eclampsia respectively. No significant effects were seen on perinatal mortality, average birth weight, deliveries after 40 weeks, hypertension in the absence of oedema and proteinuria, duration of labour, sepsis or breast-feeding occurrence. Later controlled trials with vitamins or minerals given in the same amounts as in this trial have largely failed to show convincing effects as seen here. A controlled trial assessing the isolated effects of fish oil in pregnancy is warranted.