Table 1.

Ultrasound-dated preterm birth prevalence and mean gestational age in malaria endemic and non-endemic areas

Country	Study years	Study designa	Ageb	N	Parity	Mean gestational age (days)	Preterm birthc (%)	Malaria exposure	References
Malawi	Pre 2009	PRCT	≤ 20–≥ 40	2149	All	270.2	16.3	29.5d	[92]
	Pre 2005	Cohort	22.8	456	All	266	20.3	NR	[97]
Mali	2010–2013	Cohort	15–45	152	PG	268.8	16.4	15.8e	[3]
	–		–	114	SG	271.5	12.3	10.5e
	–		–	325	MG	275.8	2.5	9.5e
Kenya
Control	2011–2013	PRCT	15–45	233	All	271	16.2	52.1f	[93]
Iron supplement	–			237	All	274.4	9.1	50.9
Gambia
Control	2006–2008	Peri-RCT	28.9	150	All	282.1	5.3	1.3g	[98]
Multinutrients			–	139	All	280	0.7	0.9
Benin	2008–2011	Cohort	NR	814	All	NR	9.9	34.2h	[84]
Tanzania	2008–2010	Cohort	22	28	PG,SG	272.7	NR	All exposedi	[83]
	–	–	23	93	PG,SG	279.4	NR	None exposedi
Uganda	2014	Nested PRCT	22.1	282	All	NR	9.2	2.9 to 8.6j	[94]
Papua New Guinea	2009–2012	PRCT	24.5	1941	All	274	8.6	13.6k	[95]
Burkina Faso (PALUFER)
Control	2011–2013	Peri-RCT	17.1	137	PG	269	13.9	29.3l	[2]
Iron supplemented	–	–	–	149	PG	264	27.5	37.1l
34 high-income countries	1996–2010	Mixed	NR	9.1 × 106	All	275.5	4.6–8.2	None	[96]

PG primigravidae, SG secundigravidae; multigravidae, N sample size, NR Not reported, PRCT pregnancy randomized control trial, Peri-RCT periconceptional randomized control trial

^aProvision of antenatal iron supplements stated for Malawi, Kenya (intervention arm alone), Gambia, Burkina Faso (both trial arms after first antenatal visit). Not stated for other studies or malaria non-endemic areas

^bMean, median, or range in years

^cBirth less than 37 weeks

^dAntenatal parasite prevalence from thick blood film on peripheral blood at booking and second antenatal visit

^eParasite prevalence in peripheral blood or placental blood smear

^fPrevalence estimate from at least one positive result for dipstick tests (HRP2 or pLDH for any Plasmodium species) in maternal venous or placental blood, or by P. falciparum—specific PCR tests in maternal erythrocytes from venous or placental blood, or presence of parasites or pigment in placental biopsies by histopathology. Malaria estimates include past infections in pregnancy

^gMalaria parasitaemia prevalence at enrolment in placebo cohort; sample size n = 240 (control), n = 232 (micronutrients)

^hSub-microscopic prevalence at delivery on capillary venous blood with Real-time PCR Assay for detection of P. falciparum infections

ⁱExposed or not exposed to malaria early in pregnancy

^jPrevalence by microscopy of placental blood smear (2.9%); prevalence of parasite DNA in placental blood (8.6%), and histopathologic detection of malaria infection (pigment or parasites) of placental biopsies, which includes past infection (37.2%)

^kPeripheral parasitaemia prevalence at enrolment by light microscopy and/or real time polymerase chain reaction (P. falciparum, P. vivax)

^lAcute and chronic placental malaria prevalence (presence of parasitized cells on histology). Sample size at delivery n = 89 (iron supplements, n = 92 (control))