Ključne poruke
– Moguće je da su žene koje su uzimale dodatke vitamina B 12 tijekom trudnoće poboljšale status vitamina B 12 tijekom trudnoće ili nakon poroda, što uključuje manji nedostatak vitamina B 12 i njegove više razine, u usporedbi sa ženama koje nisu uzimale dodatke vitamina B 12 , ali dokazi o tome su nesigurni.
– Učinci uzimanja dodataka vitamina B 12 tijekom trudnoće na ostale zdravstvene ishode kod trudnica ili njihove djece nisu poznati.
Implikacije za javno zdravlje
Vitamin B 12 je važan nutrijent koji pomaže održavanju zdravlja krvi i živčanih stanica tijela. Nedostatak vitamina B 12 je važan javnozdravstveni problem, osobito u zemljama sa niskim i srednjim dohotkom, s velikim opterećenjem među trudnim ženama i djecom. Niže razine vitamina B 12 u trudnoći povezuju se s višim rizikom određenih ishoda trudnoće kao što su pobačaj, slab rast djeteta unutar maternice, probleme s djetetovim mozgom ili leđnom moždinom (koji se nazivaju defekti neuralne cijevi) i niža razina statusa vitamina B 12 u dojenčadi.
Nadopuna vitamina B 12 tijekom trudnoće može pomoći u poboljšanju zdravlja i prehrane žena i njihove djece. Međutim, ovo nije istraženo u dobro provedenim istraživanjima i vitamin B 12 nije jedan od dodataka prehrani preporučen ženama tijekom trudnoće od strane Svjetske zdravstvene organizacije (SZO; specijalizirana agencija Ujedinjenih naroda odgovorna za međunarodno javno zdravstvo).
Što smo željeli saznati?
Željeli smo saznati bi li uzimanje dodataka vitamina B 12 tijekom trudnoće poboljšalo zdravlje i prehranu žena i njihove djece.
Kako je proveden ovaj sustavni pregled?
Pretražili smo klinička ispitivanja koja su proučavala nadopunu vitamina B 12 tijekom trudnoće. Usporedili smo i saželi rezultate istraživanja i procijenili pouzdanost informacija na temelju čimbenika kao što su metode istraživanja i veličina uzorka.
Što smo pronašli?
Uključili smo pet ispitivanja s 984 trudne žene. Tri su istraživanja, sa 609 trudnica, dala podatke uključene u analize. Žene koje su uzimale dodatke vitamina B 12 tijekom trudnoće imale su manji nedostatak vitamina B12 12 i njegovu višu razinu u usporedbi sa ženama koje nisu uzimale dodatke vitamina B 12 , ali dokazi o tome su nesigurni. Što se tiče anemija majke, nije bilo razlika između skupina. Uslijed ograničenih ili nedostupnih rezultata za analizu, nismo mogli procijeniti učinke nadopune vitamina B 12 na ostale ishode kao što su pobačaj, defekti neuralne cijevi i dječja kognicija (sposobnost djeteta da stekne znanje putem mišljenja, razumijevanja i osjetila).
Koja su ograničenja ovih dokaza?
Mali broj istraživanja i mala veličina uzoraka bili su ograničenje ovog sustavnog pregleda. Nisu sva istraživanja pružila podatke o ishodima koji su nas zanimali. Vrlo smo nesigurni oko rezultata.
Datum pretraživanja dokaza
U ovaj sustavni pregled uključeni su dokazi objavljeni do lipnja 2023. godine.
Oral vitamin B 12 supplementation during pregnancy may reduce the risk of maternal vitamin B 12 deficiency and may improve maternal vitamin B 12 concentrations during pregnancy or postpartum compared to placebo or no vitamin B 12 supplementation, but the evidence is very uncertain. The effects of vitamin B 12 supplementation on other primary outcomes assessed in this review were not reported, or were not reported in a format for inclusion in quantitative analyses. Vitamin B 12 supplementation during pregnancy may improve maternal and infant vitamin B 12 status, but the potential impact on longer-term clinical and functional maternal and child health outcomes has not yet been established.
Vitamin B 12 deficiency is a major public health problem worldwide, with the highest burden in elderly people, pregnant women, and young children. Due to its role in DNA synthesis and methylation, folate metabolism, and erythropoiesis, vitamin B 12 supplementation during pregnancy may confer longer-term benefits to maternal and child health outcomes.
To evaluate the benefits and harms of oral vitamin B 12 supplementation during pregnancy on maternal and child health outcomes.
We searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov , the World Health Organization International Clinical Trials Registry Platform ( ICTRP ) on 2 June 2023, and reference lists of retrieved studies.
Randomised controlled trials (RCTs), quasi-RCTs, or cluster-RCTs evaluating the effects of oral vitamin B 12 supplementation compared to placebo or no vitamin B 12 supplementation during pregnancy.
We used standard Cochrane methods. Four review authors independently assessed trial eligibility. Two review authors independently extracted data from included studies and conducted checks for accuracy. Three review authors independently assessed the risk of bias of the included studies using the Cochrane RoB 1 tool. We used GRADE to evaluate the certainty of evidence for primary outcomes.
The review included five trials with 984 pregnant women. All trials were conducted in low- and middle-income countries, including India, Bangladesh, South Africa, and Croatia. At enrolment, 26% to 51% of pregnant women had vitamin B 12 deficiency (less than 150 pmol/L), and the prevalence of anaemia (haemoglobin less than 11.0 g/dL) ranged from 30% to 46%. The dosage of vitamin B 12 supplementation varied from 5 μg/day to 250 μg/day, with administration beginning at 8 to 28 weeks' gestation through to delivery or three months' postpartum, and the duration of supplementation ranged from 8 to 16 weeks to 32 to 38 weeks. Three trials, involving 609 pregnant women, contributed data for meta-analyses of the effects of vitamin B 12 supplementation compared to placebo or no vitamin B 12 supplementation.
Maternal anaemia: there may be little to no difference for maternal anaemia by intervention group, but the evidence is very uncertain (70.9% versus 65.0%; risk ratio (RR) 1.08, 95% confidence interval (CI) 0.93 to 1.26; 2 trials, 284 women; very low-certainty evidence).
Maternal vitamin B 12 status: vitamin B 12 supplementation during pregnancy may reduce the risk of maternal vitamin B 12 deficiency compared to placebo or no vitamin B 12 supplementation, but the evidence is very uncertain (25.9% versus 67.9%; RR 0.38, 95% CI 0.28 to 0.51; 2 trials, 272 women; very low-certainty evidence). Women who received vitamin B 12 supplements during pregnancy may have higher total vitamin B 12 concentrations compared to placebo or no vitamin B 12 supplementation (mean difference (MD) 60.89 pmol/L, 95% CI 40.86 to 80.92; 3 trials, 412 women). However, there was substantial heterogeneity (I 2 = 85%).
Adverse pregnancy outcomes: the evidence is uncertain about the effect on adverse pregnancy outcomes, including preterm birth (RR 0.97, 95% CI 0.55 to 1.74; 2 trials, 340 women; low-certainty evidence), and low birthweight (RR 1.50, 95% CI 0.93 to 2.43; 2 trials, 344 women; low-certainty evidence). Two trials reported data on spontaneous abortion (or miscarriage); however, the trials did not report quantitative data for meta-analysis and there was no clear definition of spontaneous abortion in the study reports. No trials evaluated the effects of vitamin B 12 supplementation during pregnancy on neural tube defects.
Infant vitamin B 12 status: children born to women who received vitamin B 12 supplementation had higher total vitamin B 12 concentrations compared to placebo or no vitamin B 12 supplementation (MD 71.89 pmol/L, 95% CI 20.23 to 123.54; 2 trials, 144 children).
Child cognitive outcomes : three ancillary analyses of one trial reported child cognitive outcomes; however, data were not reported in a format that could be included in quantitative meta-analyses. In one study, maternal vitamin B 12 supplementation did not improve neurodevelopment status (e.g. cognitive, language (receptive and expressive), motor (fine and gross), social-emotional, or adaptive (conceptual, social, practical) domains) in children compared to placebo (9 months, Bayley Scales of Infant and Toddler Development Third Edition (BSID-III); 1 trial; low-certainty evidence) or neurophysiological outcomes (72 months, event-related potential measures; 1 trial; low-certainty evidence), though children born to women who received vitamin B 12 supplementation had improved expressive language domain compared to placebo (30 months, BSID-III; 1 trial; low-certainty evidence).
Hrvatski Cochrane. Prevela: Franciska Čanaki. Ovaj sažetak preveden je u okviru volonterskog projekta prevođenja Cochraneovih sažetaka. Uključite se u projekt i pomozite nam u prevođenju brojnih preostalih Cochraneovih sažetaka koji su još uvijek dostupni samo na engleskom jeziku. Kontakt: cochrane_croatia@mefst.hr